Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan (IEE Japan)  

© 2020 The Institute of Electrical Engineers of Japan. To investigate the breakdown mechanism in oil/PB composite insulation systems applied to power transformers, we have measured the electric field in partial discharge occurrence by the application of lightning impulse voltage using the electric field measurement system by electro-optical Kerr effect. It has confirmed that the system has sufficient time response for the measurement of the electric field during lightning impulse application. In the oil/PB composite insulation system, which has multi oil gaps, we could have confirmed the increase of the electric field of the other gaps when the partial discharge occurred in one of the oil gaps. Furthermore, we have confirmed that the obtained optical phase shift is similar to estimated value by electric field simulation.

DOI： 10.1541/ieejfms.140.325

Scopus

researchmap

Authorship：Last author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

© 2019 The Institute of Electrical Engineers of Japan. Electro-optical method is one of methods to measure the electric field in dielectric liquids. In this method, the change of the light intensity due to the applied electric field must be measured. It is well known that dielectric liquids move with flowing under high voltage application. The intensity data might include some error by the liquid disturbance. In this paper, we describe about the effectiveness of the measurement system improved in order to measure the electric field strength in a transformer oil, for the measurement of the strength in liquid moving with flowing.

DOI： 10.1541/ieejfms.139.406

Scopus

researchmap

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

© 2018 The Institute of Electrical Engineers of Japan. We have studied the electrical treeing generated in silicone gel used as an encapsulant for power electronics modules. The treeing which consist of bubbles and strings was named Pearl-chain-type treeing. Under AC voltage application, the bubble vibrated with repeating expansion and shrinkage. We have obtained new insight that the expansion of the bubble at polarity inversion was very important for the development of the tree.

DOI： 10.1541/ieejias.138.758

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical Engineers of Japan  

Silicone gels have been used as an encapsulation for power electronics modules. We investigated electric treeing in silicone gel under AC voltage. The trees in silicone gels consist of two parts: bubble and straight part. This type of tree is called pearl-chain type tree. The tree vibrates under AC voltage and its frequency of vibration was twice of the applied voltage. The diameter of bubble or the shape of whole tree evaluated the vibrating volume of tree. The large expanded tree/bubble and small expanded tree/bubble alternately appeared. The pearlchain type tree was observed under the voltage of rectangle wave. The inception voltage of tree under rectangle voltage was lower than the sine wave. The dependence of the growth patterns of the trees on the frequency of the applied voltage was investigated. At low frequencies (10 mHz ∼ 10 Hz), a bubble appeared at the tip of needle electrode, and a simple tree grew at 10 Hz. Trees had many small branches at 350 and 400 Hz and did not appear at frequencies over 450 Hz.

DOI： 10.23919/ISEIM.2017.8166592

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

In order to clarify breakdown mechanisms in insulation oil / pressboard composite dielectric system, it is effective to measure the electric field distributions. We have investigated the electric field distribution in transformer oil using Kerr electrooptic effect. At first, Kerr constant of the transformer oil was measured using the optical system. The constant was determined to be 2.0×10-15[m/V2]. Next, we measured the electric field in transformer oil in AC electric field in the order of milli-seconds. In order to reduce the error due to the fluctuation of light intensity of the laser, we used the improved optical system. As a result, we have been able to be confirmed that the change of light intensity when AC voltage application was followed to the principle of Kerr effect. In addition, as compared with the result measured by the conventional system, the result could be improved by the new system. Thus, we have been able to confirm that time series electric field measurement on the order of milli-seconds in transformer oil under AC voltage by using optical system based on Kerr effect. In the future, electric field measurement will be performed when partial discharge occurs by applying AC high voltage or pulse high voltage in insulation oil / pressboard composite dielectric system. The electric field distribution before and after the partial discharge will be measured and the breakdown mechanism will be investigated by based on the result.

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

A gel is used as the encapsulant of a power device. But there are a lot of uncertain points about the electrical properties of the gel. We have investigated the time series measurement of electric field distributions in propylene carbonate that was a dielectric liquid with large Kerr constant. The propylene carbonate dissolves polymethyl methacrylate resin and becomes gelatinous. It was considered that the relevance between the electrical properties of the gel and the liquid might become clear, if temporal change of the electric field strength could be measured in this gel. So, in this paper, we studied that the electric field strength could be measured in the gel using Kerr effect.

Scopus

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

Silicone gels have been used as an encapsulant of power electronics modules. We investigated electric treeing in silicone gel under AC voltage. The growth patterns of the trees depended on the frequency of the applied voltage. At low frequencies (10 mHz to 10Hz), a bubble appeared at the tip of needle electrode, and a simple tree grew at 10Hz. Trees had many small branches at 350 and 400 Hz and did not appear at frequencies over 450 Hz.

DOI： 10.1541/ieejias.137.458

Scopus

J-GLOBAL

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：一般社団法人 電気学会  

© 2017 The Institute of Electrical Engineers of Japan. The development of electrical tree is one factor that the breakdown occur in solid insulator. So, the study concerning the tree has been proceeded. When the silicone rubber gel made by changing the degree of cross-linking agent was used as a sample, the tree named pearl-chain-type was generated. The pearl-chain-type tree consisted of two parts: string and bubble. Branching occurred at bubble parts. In this study, the pattern of pearl-chain-type tree was observed under different frequency of applied voltage using a high speed camera. Main branche and side branch was also considered.

DOI： 10.1541/ieejfms.137.215

Scopus

J-GLOBAL

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical Engineers of Japan  

A gel, which has characteristics of both a solid and a liquid is called a "soft material", is widely used in various industrial fields. But there are a lot of uncertain points about the electrical properties of the gel. In order to understand the growth mechanism of pearl-chain-type electrical trees in a polymer gel, and investigate about the relationship between the liquids and gels for the high electric field phenomena, the electric field distribution must be measured in the gel. This paper reports on the measurement of the electric field strength in a certain gel using Kerr effect. It is interesting that Kerr constant of the gel depend on the weight percent of a solvent.

DOI： 10.1541/ieejeiss.136.1420

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Pearl-chain-type trees under AC voltage have been observed using a high-speed camera. When AC voltage (60Hz) was applied, a bubble was appeared at a tip of needle electrode in silicone gel. The bubble oscillated with 120Hz. After increasing the applied voltage, a linear tree/tube proceeded ahead a certain distance and stopped. Then the bubble was formed at the tips of the tree/tube. The speed of the part of the bubble was slower than the speed of the linear tube. The branching also occurred. This kind of tree is called pearl-chain-type tree. It was observed that the center of the bubble was located slightly from the tip inward.

DOI： 10.1109/ISEIM.2014.6870783

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In dielectric liquids subjected to a high electric field, space charges are generated due to various reasons, for example, by the injection of charges from electrodes or by ionization of the impurities and molecules. It is necessary to obtain information regarding the electric field and space charge distributions in insulating materials to ensure effective insulation, however, it is very difficult to obtain information regarding space charge in liquid. We have investigated the electric field distributions in liquid dielectrics using the Kerr elctrooptic effect. Recently, the electric field distribution in the order of milli-seconds has been able to be measured. For 1 ms immediately after an applied voltage, it is thought that space charge layer is almost never formed. So, we measured the electric field distribution for 1 ms at the applied voltage. Then, after a period of time, we measured again the electric field distribution at the second application of the voltage pulse. If there is a difference between the two, it is considered that it is caused by remnant electric charges. So, we report on the evaluation of the remnant charge in liquid.

DOI： 10.1109/ISEIM.2014.6870789

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：Japanese  

CiNii Books

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

In order to diagnose the effectiveness of electrical insulation, it is necessary to obtain information regarding the electric field distribution in insulating materials. We have investigated the measurement of electric field vector distributions in liquid dielectrics using an original method. Electric field distributions could be measured in time intervals of milli-seconds by an optical system. In this study, the electric field in a liquid containing space charges was measured, and the change in the electric field caused by the charges in the liquid was examined. Moreover, the space charge distribution in the liquid was also studied. We believe that our study can aid a better understanding of the movement of charges in liquid dielectrics. © 2013 Penerbit UTM Press. All rights reserved.

DOI： 10.11113/jt.v64.2094

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The tree growth has been usually classified to three stages
inception, propagation and runaway stage under AV voltage. When the two-dimensional (2-D) specimen of silicone rubber was used, the propagation stage was divided to two stages: straight and isotropic growth stages. 2-D specimen is useful to observe AC trees with many branches since the number of the branches of AC tree is usually larger than DC and impulse tree. When the silicone rubber is fabricated, two types of silicone gel is mixed up
one includes catalytic agent. If the mixed ratio is changed from 1:1, silicone rubber has fluidity or viscosity. In theses cases, breakdown or partial discharge phenomena also change. Under certain conditions of gel, tree has been developing with bubble-like and string-like pattern alternatively. This tree is called pearl-chain-like tree. At first the tree developed like bubble and then a projection like cone was generated on the surface of the bubble. The tip of the cone expanded and formed a new bubble. This process was repeated. If two tips of the cone are formed on the surface of the bubble, the branching occurs. The shape of tree is like pearl-chain. The pattern of the tree is usually string (or straight) channel and branching. However In the pearl-chain like tree, string channel has consisted of two channels
bubble and string. Branching has occurred at bubbles. These data is important to investigate the mechanism of tree. © 2013 Penerbit UTM Press. All rights reserved.

DOI： 10.11113/jt.v64.2102

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

It is important to obtain information about electric field and space charge distributions. We have investigated the measurement of electric field vector distributions in liquid dielectrics using an original method. We developed an optical system to measure electric field distributions on the order of milliseconds. Therefore, time series measurement of electric field distributions in a parallel plane electrode system was carried out. From the obtained field distributions, the time variation of a space charge density distribution was obtained. This is the first example in which the space charge distribution was measured at time intervals of 1 ms. (c) 2012 The Japan Society of Applied Physics

DOI： 10.1143/JJAP.51.080204

Web of Science

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Though it is said that the paperless age arrived with the spread of personal computers, the amount of office paper used shows no tendency to decrease. In general, used paper is recovered and recycled in order to preserve the environment. But labor and expense are required for the recovery of used paper and the recycled paper is lower in quality. If we could reuse used paper repeatedly without these disadvantages, for example, by using copying machines that could print again by removing the toner on used paper, it would be very convenient and ecological. We therefore studied the removal of toner from used paper by the laser ablation technique. As an optical source, an SHG-YAG laser was chosen. The energy density of irradiation with an SHG-YAG laser for the removal of toner from used paper was examined. At an energy density of approximately 12 mJ/mm2, which was the average value, the toner was removed sufficiently to allow reuse of the paper. The conditions of the laser irradiation, specifically the laser scanning speed and the number of irradiations, were studied. (C) 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(1): 814, 2012; Published online in Wiley Online Library. DOI 10.1002/eej.21214

DOI： 10.1002/eej.21214

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Computed tomography (CT) has been used for industrial application as well as its principal development in the medical field. We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using an original method based on the electrooptic Kerr effect and the CT method. In applying the CT method to the reconstruction of the electric field, a principle of the CT method has been faithfully observed, which has been one cause of error. Specifically, the region passed through by the light in the measurements was not equal to the reconstructed region and the electric field was reconstructed without consideration of the value of cells outside the region for reconstruction. To solve these problems, we suggest an improved algorithm for reconstruction using the concepts which we called actual region projection data and extension of region for reconstruction. Simulations and experiments were used to investigate the usefulness of the improved method. (C) online in Wiley Online Library. DOI 10.1002/ecj.10404

DOI： 10.1002/ecj.10404

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IOP PUBLISHING LTD  

Conducting polymers with neuron-like pattern has been polymerized by controlling polymerization conditions. These conducting polymers have been connected each other to prepare network. If the synapse function can be added to the network, artificial neural network is prepared by conducting polymer. In this paper, we consider the transmitter function using synapse-structure conducting polymer. It consists of three parts: primary circuit as presynaptic terminal, space as synaptic cleft and secondary circuit as postsynaptic structure. Dopant in conducting polymer works as neurotransmitter. Migration as well as diffusion is also considered for dopant ion to transit the space/cleft. When signals from the primary circuit came at the end of the primary circuit in electrolyte solution, the current in the secondary circuit increased because the released dopant ion transited the cleft and entered another conducting polymer. When two primary circuits was used, the current in the secondary circuit increased higher than one primary circuit. This means the synapse-structured conducting polymer system can be use as logical circuit.

DOI： 10.1088/1742-6596/358/1/012005

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Electrical insulation diagnosis requires that we obtain information about the electric field distribution and the space charge distribution in insulating materials. We have measured nonuniform electric field vector distributions in liquid dielectrics by our original method based on the electrooptic Kerr effect and the CT method. We carried out time sequence measurement of the electric field vector distribution in propylene carbonate, which is a dielectric liquid. When a DC voltage pulse of 200-ms width was applied to a parallel plane electrode system, the electric field vector distributions, which had the shape of a circle 12 mm in diameter, were measured at time intervals of 3 ms. The measurements were carried out while varying the conductivity of the liquid. The distribution a certain time after applying the voltage pulse seemed to be disturbed. Observation of the time at which the disturbance started would make it possible to determine the behavior and electrical characteristics of the liquid. We also studied the evaluation of remnant charges. (C) 2011 Wiley Periodicals, Inc. Electron Comm Jpn, 94(9): 45-51, 2011; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10351

DOI： 10.1002/ecj.10351

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

This It is necessary for electrical insulation diagnosis to obtain information about the electric field distribution in insulation materials. We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using an original method based on electrooptic Kerr effect and CT method. We developed a optical system that could measure electric field distributions of the order of a mili-second. In this study, we carried out the electric field in a liquid containing space charge. The change of the optical light intensity was measured when the voltage pulse was applied again after Ts (min.) from first sequence of applied voltage. i.e., by Ts, the amount of charge in liquid was changed. It was well known that the electric field strength in liquid containing charges was not a static field. The change of the electric field caused by charges in liquid was very interesiting. This technique might be help to know the movement of the charge in a liquid.

DOI： 10.1109/ICDL.2011.6015469

Web of Science

Scopus

J-GLOBAL

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

Computed tomography (CT) method has been used for industrial application as well as it has been mainly developed in a medical field. We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using an original method based on electrooptic Kerr effect and CT method. In applying CT method to the reconstruction of the electric field, a principle of CT method has been faithfully observed, which has been one of cause of the error. Specifically, region passing through of the light for measurements was not equal to the reconstructed region and the electric field was reconstructed without consideration of the value of cells outside of the region for reconstruction. So, to solve these problems, we suggested the improved algorithm for reconstruction using the concepts which we called "actual region projection data" and "extension of region for reconstruction". By a simulation and an experiment, the usefulness of the improved method was studied. © 2011 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.131.472

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using an original method based on electrooptic Kerr effect and CT method. Recently, we developed an optical system that could measure electric field distributions of the order of a mili-second. The temporal change of the electric field distribution obtained by this system would allow us to study a behavior of a space charge and an electrical conduction in liquid insulations. In this study, we carried out the electric field in a liquid containing space charge. The space charge could not be evaluated quantitatively, so liquids left for scores of minutes from the first sequence of the applied voltage were used. By changing the time required for leaving, the quantity of charge in liquids was changed. It was well known that the electric field strength in liquids containing charges was not a static field. The change of the electric field caused by charges in liquids was very interesting.

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

The Development of breakdown in solid/gel insulators under AC voltage has been observed using the different mixed ratio silicone rubbers. Discharge phenomena in double composite silicone rubber has been also observed and the its model has been suggested.

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

For electrical insulation diagnosis, it is necessary to obtain information about the electric field distribution and the space charge distribution in insulation materials. We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using an original method based on the electrooptic Kerr effect and the CT method. We developed an optical system that could measure electric field distributions in about 1 ms. In this study, when a DC voltage pulse of 50 ms width was applied to a sphere-to-plane electrode system, electric field distributions on some measurement planes were measured at intervals of 1 ms. The distribution a short time after application of the voltage pulse seemed to be disturbed. It is inferred that the "disturbance" was caused by changes in the density of the liquid due to movement of certain carriers in the liquid. Observation of the time of onset of the disturbance would make it possible to determine the behavior and electric characteristics of the liquid. (C) 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(1): 1-9, 2010; Published online in Wiley Inter Science (www.interscience.wiley. com). DOI 10.1002/eej.20940

DOI： 10.1002/eej.20940

Web of Science

Scopus

J-GLOBAL

researchmap

Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

本記事に「抄録」はありません。

DOI： 10.1541/ieejjournal.130.243

CiNii Books

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Conducting polymers has been polymerized on a bottom of the vessel/cell under certain conditions, and the patterns of two-dimensional (2-D) conducting polymer have become fractal. A neuron-like conducting polymer can be fabricated by changing the polymerization conditions under polymerization. The pattern of conducting polymer network depends on the polymerization/environment conditions. The conducting polymer has many functional properties. if conductivity at paths in the network depends on signals that flow the paths, a neuron-like device can be prepared. In this process, it is hard to control the transition of the polymerized points from the surface of the electrode to the vessel. The pattern depends on the time of transition because the concentrations of monomer and electrolyte decrease with time. In some conditions, transition never occurs. In this paper, the initiation conditions of neuron-type conducting polymer have been investigated. It is found that concentrations of oligomer/polymer that did not attach myself to the electrode is the important factor for the transition of polymerized points from on the electrode to on the surface of the vessel. (C) 2009 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.synthmet.2009.08.044

Web of Science

Scopus

researchmap

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

It is necessary for electrical insulation diagnosis to obtain information about the electric field distribution and the space charge distribution in insulation materials. We have measured nonuniform electric field vector distributions in liquid dielectrics using our original method based on electrooptic Kerr effect and CT method. We carried out the time sequence measurement of electric field vector distribution in propylene carbonate which is a dielectric liquid. When the DC voltage pulse of 200msec width was applied to a parallel plane electrode system, electric field vector distributions, which had a shape of the circle with 12 mm in diameter, were measured at the time interval of 3 ms. The measurements were carried out with changing the conductivity of the liquid. The distribution after a while from applying the voltage pulse seemed to be disturbed. The observation of the time that started the disturbance would be able to give the behavior and electric characteristic of the liquid. Moreover, we studied about the evaluation of remnant charges. © 2009 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.129.307

Scopus

J-GLOBAL

researchmap

Language：Japanese   Publishing type：Research paper (scientific journal)  

Though it is said to the paper-less age with the spread of personal computer, amount of office papers to be used doesn't have tendency to decrease. In general, used papers are recovered and recycled in order to preserve the environment. The labor and costs are required for the recovery of used papers and a recycled paper is lower in quality. If we could reuse used papers repeatedly without withdrawing those, for example, by copying machine that could print again with removing toner on used paper, it is very convenient and ecological. So, we studied about removing toner from used papers by application of the laser ablation technique. As an optical source, SHG-YAG laser was chosen. For removal of toner from used papers, the energy density to irradiate them with SHG-YAG laser was examined. When approximately 12mJ/mm2 of the energy density, which was average value, toner was removed so much as to be able to reuse again. Moreover, conditions of the laser irradiation, concretely, the velocity scanning the laser and the number of the irradiation, were studied. © 2009 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.129.205

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INST ELECTR ENGINEERS JAPAN  

It is necessary for electrical insulation diagnosis to obtain information about the electric field distribution and the space charge distribution in insulation materials. We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using an original method based on electrooptic Kerr effect and CT method. We carried out the time series measurement of electric field vector distribution in propylene carbonate. When the DC voltage pulse of 50msec width was applied to a sphere-to-plane electrode system, electric field vector distributions on some measured planes were measured at intervals of 1 ms. Distribution at starting voltage pulse was almost the same as that of a static field. The electric field vector distribution seemed to be disturbed after a certain time, and the electric field vector distribution could not be measured after it. But, the observation of the time when the "disturbance" started would be able to give the behavior and electric characteristic of the liquid.

DOI： 10.1109/ISEIM.2008.4664483

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

For electrical insulation diagnosis, it is necessary to obtain information about the electric field distribution and the space charge distribution in insulation materials. We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using an original method based on electrooptic Kerr effect and CT method. We developed a optical system that could measure electric field distributions in about 1 ms. In this study, when the DC voltage pulse of 50 ms width was applied to a sphere-to-plane electrode system, electric field vector distributions on some measured planes were measured at intervals of 1 ms. The distribution after a while from applying the voltage pulse seemed to be disturbed. It was considered that the "disturbance" was caused by the change of the density of the liquid due to moving of the liquid with certain carriers. The observation of the time that started the disturbance would be able to give the behaviour and electric characteristic of the liquid. © 2008 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.128.209

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

The development mode of the AC tree can be classified into three modes
(i) straight mode, (ii) isotropic mode and (iii) selected branch mode. The development of the tree in diffusion mode means that an envelope of the tips of the branches spreads as diffusion. This development has been considered. An AC tree in silicone rubber sample has disappeared after applied voltage. Behavior of the disappearance of trees is different in 2-dimensional (2-D) and 3-dimensional (3-D) sample in which needle electrode system was set up. The branches of 2-D tree are survived longer than the branches of the 3-D tree. © 2008 The Institute of Electrical Engineers of Japan.

DOI： 10.1541/ieejfms.128.263

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INST ELECTR ENGINEERS JAPAN  

Trees in silicone rubber has been investigated using 2-D specimen. The tree is classified two, i.e. 1st and 2nd tree. The behaviors of these trees have been observed by changing the ratio of two components of silicone rubber. The 1st tree is usually linear but the bubble has been formed in the soften silicone rubber. When the 1s tree is round babble, it is difficult for the 2nd tree to start from it. The speed of the 2nd tree in harden silicone rubber is higher in harden silicone rubber. The mechanism of tree in silicone rubber can be considered, and the pressure inside the tree is suggested to be important factor.

DOI： 10.1109/ISEIM.2008.4664493

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English  

This paper presents experimental results of NO removal from a simulated exhausted-gas using a barrier type reactor with screw electrodes subjected to polarity-reversed voltage pulses. The polarity-reversed pulse was produced by direct grounding of a charged coaxial cable because a traveling wave voltage was negatively reflected at the grounding end with a change in its polarity and then it propagated to the plasma reactor at the opposite end. Influence of cable length on NO removal was studied for two kinds of cable connection, single-connected cable and parallel-connected cables. NO removal ratio for a 50m-long cable was lower than that for much shorter cables in both single and parallel connections when the applied voltage became high. Energy efficiency for NO removal also increased with decreasing the cable length. This was because excess discharges during the voltage oscillation caused by the large stored energy in the long cable resulted in reproduction of NO molecules. Energy efficiency was further improved by changing the discharge mode from dielectric barrier discharge (DBD) to surface discharge (SD). Energy efficiency was up to 110g/kWh with 55% NO removal ratio and 34g/kWh with 100% NO removal ratio by using a single 10m-long cable in SD mode.

DOI： 10.1541/ieejfms.127.553

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Writing/non-writing of composite conducting polymer (polypyrrole/poly(3-hexylthiophene)) have been investigated using composite conducting polymer. Writing has been made in two processes: pretreatment and dropping ethanol. The unipolar signal (10 Vp-p, 10 Hz+5 VDC) has worked as a circuit signal. The conductivity at the path of the composite conducting polymer network has depended on the passed signal. It was confirmed using the Y-type and H-type composite conducting polymer. It has been confirmed that rewriting of composite conducting polymer is possible to develop a memory or a neural network device of conducting polymer.

DOI： 10.1093/ietele/e89-c.12.1732

Web of Science

Scopus

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

By controlling electrochemical polymerization conditions the linear conducting polymers have been fabricated not on the electrode but on the bottom of the cell. The Y-shaped one was also fabricated. The important factors are to change the concen-tration of monomer during polymerization and to make the groove on the surface of the bottom. It is suggested that the linear network of conducting polymer can be fabricated by controlling the polymerization conditions.
In order to add the learning effect to the conducting polymer, the composite two-dimensional conducting polymer has been used. Whether the composite polymer was pretreated or not can be checked by dropping ethanol. This method can be used for memory or learning effect of conducting polymers. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.tsf.2005.07.011

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Conducting polymers with a fractal pattern have been prepared electrochemically and have been connected to each other. A network of conducting polymers similar to a neural network has been fabricated. The dopant used in the channels of the network of conducting polymers can be controlled by the current through the channels utilizing the property of a gel-conducting polymer such as poly (alkylthiophene). Thus the signal weight of the network of conducting polymers depends on the signals that flow through the network. This is called teaming effect. In the case of a network of a single conducting polymer, it is hard to control the conductivity in the channels. In this paper, double or triple-layer conducting polymers have been used to achieve stable operation. Furthermore an alternative (sine wave) signal has been used to investigate the teaming effect on the double layer conducting film.

DOI： 10.1016/j.synthmet.2005.07.106

Web of Science

Scopus

researchmap

Language：English  

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

In spite of the spread of personal computer, amount of office papers to be used does not have tendency to decrease. In general, the used papers are withdraw and recycled in order to preserve the environment. If used papers could be reused repeatedly without withdrawing those, it is very convenient. So, we try to remove toner from used papers using some kinds of laser, and concluded that second harmonic YAG laser was one of useful laser. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejeiss.125.983

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INST ELECTR ENGINEERS JAPAN  

For electrical insulation diagnosis, it is necessary to obtain information about the electric field distribution and the space charge distribution in insulation materials. We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using an original method based electrooptic Kerr effect and CT method. By the way, nitrobenzene has often been used in Kerr effect measurements because its Kerr constant is very larger than other liquids. However, nitrobenzene belongs to deleterious substances and it is very difficult to treat it. In contract, propylene carbonate is much safer and its Kerr constant is comparable to nitrobenzene. In addition, it is very interesting to measure the change of the electric field distribution because propylene carbonate has a strong dipole. In this paper, we will report on the measurement of the electric field vector distribution changing with time in ms order when a voltage pulse or DC voltage was applied to a electrode system in propylene carbonate nitrobenzene, and both was compared.

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INST ELECTR ENGINEERS JAPAN  

Although electrical trees in silicon rubbers silicone rubbers have been observed, AC trees have many small branches and thus it is hard to measure it three-dimensionally. In order to observe the patterns of AC trees, two-dimensional sample is used. The development mode of the tree has been classified into three modes; Just after generating the tree, (i)the AC tree has developed straightly. Then the branches has started and (ii)the envelope of the top of the branches has developed coaxially. When one of the branches reached at some point, (iii) that branch developed faster than others and then breakdown occurred. It is known that trees disappear in silicon rubbers after some hours. Trees in two- or three-dimensional silicon rubbers have been compared. Small branches has disappeared after 24 hours in 3-D sample. In 2-D samples, trees did not disappear as ones in 3-D samples.

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

Two-dimensional (2D) patterns of a conducting polymer have been prepared electrochemically. The patterns depend on the conditions of electrochemical polymerization. Concerning the polymerization reaction and the growth process of conducting polymers, it is found that the growth rate and solution flow during the generation of the 2D pattern are important factors for controlling the 2D pattern. The linear pattern and the simple branching pattern were successfully fabricated by optimizing the deposition conditions. The successful fabrication of the branching pattern indicates the processability of linear conducting polymers for network formation.

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The focus of acoustic partial discharge measurements is based on the discharge location. The tank wall thickness of a power transformer is usually larger than the wavelength of the signal, and therefore possesses a path for the signal, thereby complicating the triangulation procedure for the determination of the discharge location. Owing to their difference in frequency, the signals that travel faster through the mixed path of oil and tank and the slower ones that follow a direct path through oil can be differentiated. By using wavelet transform, we are able to not only discriminate between these two signals, but also to determine the exact instant at which a change in the detected signal occurs due to their interference. This is a new method of analyzing the partial discharge acoustic signal to extract the signal that travels through the direct path in oil and can lead to a more accurate discharge location.

DOI： 10.1143/JJAP.42.5347

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Conducting polymers with fractal patterns have been polymerized electrochemically under some conditions. The pattern of neuron-like conducting polymer has been prepared by controlling the polymerization conditions. Furthermore, the network of neuron-like conducting polymer has been prepared. If this kind of conducting polymer has the properties of learning effect and non-linearity, it works as neuron device. In this article, the method for adding the learning effect to the channel of conducting polymer has been investigated. In conducting polymer gels, the dopant easily moves in or out of conducting polymers in some solvents and in this time the gel swells or shrinks. On the other hand, polypyrrole is stable in such solvents. A composite film of polypyrrole and conducting polymer gel, poly (3-hexylthiophene), has been used to suppress the change of shape of conducting polymer gel. The technique of neural network was used as a method of learning effect. A simple network has been used instead of actual complicated conducting polymer network. It was confirmed that the conductivity of the channel network changed for correspondence to a teacher signal flow. (C) 2003 Elsevier B.V. All rights reserved.

DOI： 10.1016/S0040-6090(03)00764-8

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The focus of acoustic partial discharge measurements is based on a partial discharge source location, and therefore knowledge of the acoustic signal propagation path is important. Numerical simulation of wave propagation in a model transformer is carried out to aid in the interpretation of the laboratory measurements in as far as the delay time of the various peaks is concerned. The simulated signals and the experimentally measured signals are in good agreement. We are able to determine the signal propagation path and to explain the waveform profile depending on the position of the acoustic emission sensors attached to the model transformer tank wall. The numerical simulation is carried out by solving the three dimensional (3D) wave equation using the finite-difference method. Of particular interest are the boundary conditions and choice of grid size to minimize the dispersion error.

DOI： 10.1143/JJAP.42.3686

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Electrical Engineers of Japan  

We have already reported on reconstructions of symmetrical and nonsymmmetrical electric field vector distribution using Kerr electrooptic effect and our unique reconstruction method modified computed tomography technique. This reconstruction technique gives electric field map, i.e., the strength and the direction of electric field vector, on any plane. If electric field distribution is obtained continuously with time, the measutement of electric field distribution is more useful. So we try time series measurement of electric field distribution. © 2003, The Institute of Electrical Engineers of Japan. All rights reserved.

DOI： 10.1541/ieejfms.123.600

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Patterns of electrical trees in insulators have been investigated numerically using fractal dimension. The complexity of the pattern of the tree increases with applied voltage. The degree of the complexity depends on the polarity of the applied voltage. The change of the pattern of the tree can be indicated by the fractal dimension. However, in high voltages the fractal dimensions of the trees are almost same one in both polarities. This means that the pattern of the tree consist of some fractal patterns. Thus we must focus on the local pattern of the tree which is estimated by local fractal dimension.
In this paper, the pattern is analyzed by the local fractal dimension method, i.e. local fractal dimension map and local fractal. dimension spectrum. The needle electrode in a silicon rubber has been applied three or four times with impulse voltage. The local fractal dimension maps and its spectra have been compared and then the next growth of the tree or branches has been predicted using the local fractal dimension map. In addition, the change of the local fractal dimension of the tree along the branch has been investigated.

DOI： 10.1109/ICPADM.2003.1218562

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We have been investigating the determination of three-dimensional electric field distributions using an original method. We have already reported on measurements of symmetrical and nonsymmetrical electric field vector distributions. This reconstruction technique gives electric field map, i.e., the strength and the direction of electric field vector, on any plane. If electric field distribution was obtained continuously with time, the measurement of electric field distribution is more useful. So, we propose continuous measurements of electric field vector distribution in a liquid insulator. The measurement system is called simultaneous three-directional optical measurement system with parallel processing. The term of "parallel processing" means that the signal for each image sensor was processed simultaneously. By this system, the electric field distribution was measured at intervals of 1 ms when a voltage pulse was applied to an electrode system.

DOI： 10.1109/ICPADM.2003.1218465

Web of Science

Scopus

researchmap

Language：Japanese   Publisher：一般社団法人電子情報通信学会  

導電性高分子を電解重合法を用いて重合する際に重合条件を選べば,枝分かれ成長する導電性高分子を得ることができる.特に,重合中,条件を変化させていけば,ニューロン型の導電性高分子が得られる.このニューロン型導電性高分子は接続可能で,ネットワーク状のものを得ることもでき,このネットワークに導電性高分子の機能を付加することにより,新しいデバイスの可能性が出てくる.ネットワークの形は重合条件に依存するが,これは環境条件にも依存するということで,環境を形態に取り込んだデバイスが考えられる.形状を考慮するためにDLAモデルを改良したシミュレーションも行った.

CiNii Books

researchmap

Language：English   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

Web of Science

researchmap

Language：English  

DOI： 10.1109/TDEI.2002.1115492

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

We have been investigating the determination of three-dimensional electric field distributions using the reconstruction technique modified by the computed tomography technique and the Kerr electrooptic method. For the reconstruction using this technique, the light intensity must be measured from many directions around the measured distribution. Therefore, we studied the effect of the number of measurement directions on the reconstructed electric field distributions.

DOI： 10.1143/JJAP.41.5478

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

We have been investigating the determination of three-dimensional electric field distributions using an original method. The method combines the reconstruction technique modified by the computed tomography technique and the Kerr electrooptic method. We have already reported on measurements of symmetrical and nonsymmetrical electric field vector distributions. By developing a simultaneous three-directional optical measurement system of parallel processing, we were able to carry out time series measurements of the electric field distribution in ms order. We report on the measurement of the electric field vector distribution changing with time on a circular area in a sphere-plane electrode system.

DOI： 10.1143/JJAP.41.L861

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：SCRIPTA TECHNICA-JOHN WILEY & SONS  

We have already reported on reconstructions of the symmetrical and nonsymmetrical electric field vector distribution using the Kerr electrooptic effect and our unique reconstruction method, a modified computed tomography technique. This reconstruction technique gives an electric field map, that is, the strength and the direction of the electric field vector, on any plane. For the reconstruction of one field vector distribution, it was necessary to measure the light intensity twice while changing the optical axis of optical wedges. Moreover, the intensity measurement must be carried out at many points around the electrode system. Therefore, considerable time was required to measure the electric field distribution. We therefore developed a simultaneous three-direction optical measurement system with three optical systems combined with the two-beam method. Using the new measurement system, we measured the electric field distribution on planes in a sphere-to-sphere electrode system. It took about 0.1 second to measure the light intensity data for the reconstruction. (C) 2002 Scripta Technica.

DOI： 10.1002/eej.1141

Web of Science

Scopus

researchmap

Language：Japanese   Publisher：The Institute of Electrical Engineers of Japan  

Model trees have been analyzed with multifractal of general fractal and global spectrum trees in polymer. However these results do not have information of the place. It is difficult to consider the mechanism of the development of the tree. The new method of local fractal dimension map is proposed to analyze the electrical tree. At first model trees of both polarities have been analyzed with the conventional and the new method. Actual impulse trees for both polarities have been also analyzed. The branching in the progress can be estimated quantitatively.

DOI： 10.1541/ieejfms.122.198

CiNii Books

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

We have carried out measurements of three-dimensional nonuniform electric field distribution using Kerr electrooptic measurement with a reconstruction technique. A conventional measurement system was composed of He-Ne laser, a polarizer, a quarter-wave plate, an experimental cell, an analyzer, and a photo-detector. For the measurement of an electric field vector distribution, it was necessary to measure light intensity with changing the optical axis of optical wedges, i.e., the polarizer, the quarter-wave plate and the analyzer. Moreover, the intensity measurement must be carried out at many points from theta = 0 to pi around the electrode system. Therefore it took considerable time to measure the electric field distribution. We have improved the measurement system by a cell with six optical windows and three optical systems. Using the improved measuring system, it was possible to measure the non-uniform electric field vector distribution faster.

DOI： 10.1109/94.983885

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

In this paper, we present a three-dimensional numerical simulation of partial discharge (PD) acoustic wave propagation that has been developed to provide time-domain signal representation in a model transformer. The numerical modeling of acoustic PD data is used to support interpretations of laboratory experimental data and to enhance the understanding of acoustic wave propagation in a structure like the power transformer, and hence PD source location in the same. It is intended that an extension of the work presented here, to account for real transformer geometry and also to visualize the propagation of acoustic wave fronts, will later be compared with field results. The three-dimensional wave equation, given by c(2)del(2)P=partial derivative(2)P/partial derivativet(2), where c is the acoustic velocity and P the pressure wave field, defines an initial value problem and describes time evolution. The goal of the numerical code is to track that time evolution with some desired accuracy taking into consideration the boundary conditions that govern the evolution in time of points on the boundary of the spatial region of interest. This is particularly important for the satisfactory modeling of a complex structure like power transformer. In solving the above equation using finite-difference method, of particular interest are the conditions of numerical stability. In this paper we apply the stability analysis method originally developed by Von Neumann. The simulation results are in agreement with the results obtained from the laboratory experiments.

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We have investigated the measurement of nonuniform electric field vector distributions in liquid dielectrics using the optical method based electrooptic Kerr effect Our reconstruction technique of the electric field distribution has a merit that the strength and the direction of the electric field at each position can be known. But the method had a problem of a measurement time. So we developed a new optical system that could measure reconstruction data simultaneously from three directions. Using this system, we measured continuous electric field distributions.

Web of Science

Scopus

researchmap

Many researchers have studied the Partial Discharge (PD) source location in transformers using acoustical methods. However, most of these studies have treated the transformer as a homogeneous medium, thus rendering the location of discharges inside the transformer winding difficult. In this paper we present a 3-D computer simulation of the PD acoustic signal propagation path in an attempt to locate the PD source. The computer simulation is in agreement with experimental data obtained from the laboratory. Further, the effect of the real transformer tank on the acoustic signal is studied with an aim of distinguishing the various frequency dependent signal components that are detected by the Acoustic Emission (AE) sensor. This is particularly important in explaining the acoustic coupling between oil and transformer tank material and for determining the propagation velocities when determining the PD source location.

Scopus

researchmap

Patterns of electrical trees in insulators is estimated numerically by fractal dimension. However they are not simple fractal but multifractal. They can be estimated by global spectrum and singularity, which do not have local information clearly. A local fractal dimension and its spectrum are introduced. Local fractal dimension maps of impulse trees were calculated and its development is considered by it and its spectrum. The change of the pattern of the impulse trees in applying next impulse voltage can be predicted by considering the difference in the local fractal dimension spectrum in each stage.

Scopus

researchmap

The location of partial discharge is tried using the ultrasonic wave of partial discharge. At present, the experiment is carried out in the simple model of the transformer. Peaks of the simulated ultrasonic wave appeared in the time which was almost equal to peaks of actual ultrasonic wave. And, the ratio of the amplitude of the ultrasonic wave was also almost in agreement. The simulation was able to reproduce the ultrasonic wave by partial discharge in two dimensions. The experimental system was simulated, and the transmission was confirmed in two dimensions.

Scopus

researchmap

The reconstruction technique of a electric field distribution which we developed has a merit that the strength and the direction of the electric field at each position on any measured plane can be determined. In order to reconstruct a field vector distribution, it was necessary to measure light intensity twice with changing the optical axis of optical wedges. Moreover, the intensity measurement must be carried out at many points around the electrode system. Therefore we developed a new measurement system with three sets of a optical system with a non-polarizing beam splitter and two image sensors because it took considerable time to measure an electric field distribution. It took a short time, less 100 ms, to map the field distribution using the new measurement system. And the measurement of the electric field distribution at intervals of 40 ms. became possible by the new system. So, we measured of the field distribution every 40 ms in a sphere-to-sphere electrode system, when a negative DC voltage was applied to the electrode system. The obtained results were very interesting.

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Neuron-type conducting polymers have been prepared electrochemically. The pattern of the network of neuron-type conducting polymers depends on the experimental or environmental conditions. The weight of the path in the network depends on the shape and the number of the path between the sites. If this network of conducting polymer is packed to produce a new device, the device will contain the environmental conditions. Furthermore, the device has the characteristics of a synapse; it works as neuron device. It is proposed that the conducting polymer gel be used so that a learning effect is added to the path of the network. In the process of swelling or shrinking under some solvents, the dopant moves in or out of the conducting polymer Gel. However, it has been found that the dopant in the path does not easily move out even in the poor solvent when an a.c. voltage of one polarity has been applied to the conducting polymer under the liquid-phase doping. Therefore, this treatment is used in the learning effect or the memory effect, i.e. the learning current or voltage is applied to the neuron-like network conducting polymer doped in liquid phase, dry it and drop the poor solvent on the path. Hence, this network has many paths with various resistivities. (C) 2001 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0040-6090(01)01126-9

Web of Science

Scopus

researchmap

Language：Japanese  

CiNii Books

J-GLOBAL

researchmap

Language：Japanese  

CiNii Books

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

The learning effect of the neuron-like conducting polymer is considered to produce to the network device with the shape and functions of the neuron. The conducting polymer gel has been investigated to add the learning effect on the path between the neuron-like conducting polymers. AC and DC voltage was applied to the conducting polymer gel as pretreatment during the liquid-phase doping. After pretreatment the ethanol was dropped out the path and the change of the current was measured. It was found that AC voltage works as learning effect.

DOI： 10.1016/S0379-6779(00)01510-1

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

We have investigated nonuniform electric field vector distributions in liquid dielectrics. We have already reported on measurements of symmetrical and nonsymmetrical electric field vector distribution using the Kerr electrooptic effect and our unique reconstruction method based on the computed tomography technique. For the measurement of a field vector distribution, it was necessary to measure light intensity twice by changing the optical axis of optical wedges. Moreover, the intensity measurement had to be carried out at many points around the electrode system, and therefore it took considerable time to measure an electric field distribution. Thus, we developed a simultaneous three-direction optical measurement system with three optical systems combined with a two-beam method. Using the new measurement system, the electric field vector distribution was measured in about 0.1 min.

DOI： 10.1143/JJAP.40.914

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

Trees in insulators have been investigated using fractal geometry. The complexity of the tree is estimated by only one number of the fractal dimension. in some cases that the local shape of the branches of the trees is different in another branches, it is not useful to analyze whole tree. Tree should be multifractal. Therefore multifractal analysis is done and then a global spectrum is obtained. It is, however, difficult to understand the curve of the global spectrum (Global dimension and singularity) because both numbers mean dimension. We sometimes need a local information on the tree. Multifractal, however, does not tell us it because the local information is lost when it is calculated. We suggested new numerical method for trees; local fractal dimension. Fractal dimension at each point on the tree is calculated. The correlation function is used for estimating local fractal dimension. We furthermore suggest wavelet analysis instead of correlation function. For the correlation function, the area calculated is determined by someone. In the case of wavelet function, the area is, however, automatically determined, because the wavelet function changes their supported region automatically. It is easy to point out the change of the tree and it is useful to estimate the development of the tree using these methods.

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We have investigated nonuniform electric field vector distributions in liquid dielectrics. We have already reported on measurements of symmetrical and nonsymmmetrical electric field vector distribution using Kerr electrooptic effect and our unique reconstruction method modified computed tomography technique. The measurement system was composed of a He-Ne laser, a polarizer, a quarter-wave plate, an experimental cell, an analyzer, and a photo-detector. For the measurement of a field vector distribution, it was necessary to measure light intensity twice with changing the optical axis of optical wedges. Moreover, the intensity measurement must be carried out at many points from theta =0 to pi around the electrode system. Therefore it took considerable time to measure an electric field distribution. So, We developed a simultaneous three-direction measurement system with three optical systems mixed the two-beam method.
Using the new measurement system, the electric field vector distribution was measured in 0.1 minutes.

Web of Science

Scopus

researchmap

Discharge patterns in liquid can be analyzed by multifractal. The growing mode of the pattern of discharge also classified using global spectrum. It is, however, difficult to understand the curve of its global spectrum, because its spectrum loses information on the location of the pattern. Local fractal dimension map is proposed to analyze development mechanism of tree-like discharge and local fractal dimension spectrum is also calculated from the map. Fourier transform of the local fractal dimension map can be available to analyze branches of the discharge tree.

Scopus

researchmap

We have been carried out the measurement of three-dimensional nonuniform electric field distributions using Kerr electrooptic measurement with a reconstruction technique. A conventional optical system was composed of a He-Ne laser, a polarizer, a quarter-wave plate, an experimental cell, an analyzer, and a photo-detector. For the measurement of a field vector by the system, it was necessary to measure light intensity twice with changing the optical axis of three optical wedges, i.e., the polarizer, the quarter-wave plate and the analyzer. Therefore it took considerable time to measure the electric field distribution. So, we improved the optical system. For the improvement, new expression of the relationship between measured light intensity and a phase shift due to Kerr effect was derived. The optical system improved made it possible that the electric filed distribution was measured faster. The measured distributions were compared with the theoretical ones calculated by analytical method, and they corresponded well.

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：INST PURE APPLIED PHYSICS  

The three-dimensional nonuniform electric field vector distribution was measured in a nonsymmetrical electrode system using the Kerr electrooptic effect with the reconstruction technique modified by computed tomography (CT). The intensity of the light transmitted through a dielectric liquid in nonuniform field was detected at many points on one plane. It was found that the nonuniform electric field in the liquid can be measured three-dimensionally and visualized.

DOI： 10.1143/JJAP.38.6170

Web of Science

Scopus

researchmap

Language：Japanese  

CiNii Books

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE SA  

Neuron-like conducting polymers have been prepared electrochemically. Many conducting polymers with fractal patterns have been connected. Input pulse was divided into two. One was actual input signal and another one was applied a third electrode to control weight of the network path, which means conductivity of the channel between branched conducting polymer sites. The weight of the path varied with the number of the input pulses. The neuron-like conducting polymer could be laminated because of a new device and is very flexible.

DOI： 10.1016/S0379-6779(98)00990-4

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

We carried out the measurement of the three-dimensional nonuniform electric field distribution in a non-symmetrical electrode system, An optical system was composed of a He-Ne laser, a polarizer, a quarter-wave plate, an experimental cell, an analyzer, and a photo-detector, When a negative high voltage pulse was applied to the electrodes system, the light intensity transmitted to the analyzer was measured by the photo-detector, The intensity measurement was carried out at many points in each direction from 0 to pi. From the obtained data, the electric field distribution was reconstructed with algebraic reconstruction technique (ART) in computed tomography (CT) technique, The measured distribution was interesting.

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN J APPLIED PHYSICS  

An electrooptic method is useful for measuring electric fields without disturbing them. Our investigations have been concerned with measurements of electric field distribution. Three-dimensional nonuniform electric field distributions were measured in nitrobenzene using the Kerr electrooptic measurement. The field distributions to be measured were produced in a sphere-to-sphere electrode system. The optical system consisted of a He-Ne laser, a polarizer, a quarter-wave plate, an experimental cell, an analyzer, and a photodetector. When a negative high voltage pulse was applied to the electrode system, the light intensity transmitted to the analyzer was measured using the photodetector. Intensity measurements were carried out at many points from theta = 0 to tau around the electrode system. From the data obtained, the electric field distribution, i.e., the strength and direction of each electric field vector in the measured plane, was reconstructed using a computed tomography (CT) technique. The measured distributions were compared with the theoretical ones calculated using an analytical method.

DOI： 10.1143/JJAP.35.4550

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

Kerr electrooptic method is useful in measuring electric fields. Three-dimensional nonuniform electric field distributions were measured in dielectric liquids, nitrobenzene and transformer oil, by Kerr electrooptic measurement. The held distributions were measured in sphere-to-sphere electrodes systems. An optical system was composed of a Re-Ne laser, a polarizer, a quarter-wave plate, an experimental cell, an analyzer, and a photo-detector. When a negative high voltage pulse was applied to the electrodes system, the light intensity was measured by the photo-detector. The intensity measurement was carried out at many points in each direction from 0 to pi. From the obtained data, the electric held vector distribution was reconstructed by algebraic reconstruction technique (ART). The measured distributions were compared with the theoretical ones calculated by electric image method.

Web of Science

Scopus

researchmap

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN J APPLIED PHYSICS  

We have developed a culculation method of the applied electric field in a dielectric by measuring the difference in the output light intensity. At present, the direction of each applied field can be calculated when the dielectric is divided into four cells in which the applied fields are the same in intensity but differ in direction. Firstly, this paper shows how to determine the applied field intensity and direction when the electric field is applied to only one dielectric cell. Secondly, the method of numerical calculation of the applied field is described applying the method for one cell to a case where the dielectric is divided into two cells in which the intensity of the applied field is known but the direction is unknown. Finally, by extending the case of two cells, the flow of the numerical analysis and its result are described when the dielectric is divided into four cells under the same conditions as those for the two-cell case.

DOI： 10.1143/JJAP.34.336

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN J APPLIED PHYSICS  

We have been investigating a nonuniform electric field measurement method in dielectric liquids using the Kerr electrooptic effect. Three-dimensional electric field vectors were measured as the first step in determining the three-dimensional nonuniform electric field distributions. The electric field vector to be measured was produced in a pair of inclined parallel-plane electrodes. Negative high-voltage pulses were applied to the electrode system. Nitrobenzene with large Kerr constant was used in the experiments. A He-Ne leaser beam passed through nitrobenzene between the electrodes along two different orthogonal directions. The magnitude and the direction of the electric field vector were calculated from the light intensity measured by a photodiode. Maximum errors of measured electric field strength and direction were 9.3% and 4.3-degrees, respectively.

DOI： 10.1143/JJAP.33.2066

Web of Science

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

Electric field map in three dimension has been able to draw using Kerr electro-optic effect and CT(computer tomography) method. Two-dimensional electric vectors and vector distribution could also be measured successfully by many workers. Extending this method, the authors have developed the method in which three dimensional vector components has been determined by input to output ratios along two orthogonal direction. In that case, three dimensional Kerr effect should be formalized from conventional Kerr effect equation.

Web of Science

Scopus

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

Web of Science

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

An optical method using the Kerr effect is useful to measure electric fields in dielectric liquids without disturbing the field. A conventional relation of the Kerr effect cannot be applied to the measurement of a three-dimensional field, the direction of which is not always perpendicular to an incident light. We have derived the relation of the Kerr effect which can be applied to three-dimensional measurement and confirmed it experimentally. © 1993 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.32.4854

Scopus

researchmap

Language：Japanese   Publisher：The Society of Materials Engineering for Resources of Japan  

It is very important to measure the electric field-strength in an insulator to understand a mechanism of dielectric breakdown. Recently, the development of the optoelectronics and the computer has been helped the measurement of electric field-strength in a liquid dielectric by optical method using the Kerr effect The sample liquid was nitrobenzene which has the Kerr constant of 3.62×10<SUP>-12</SUP>m/V<SUP>2</SUP>. Two test cells were used one was a brass coaxial cylindrical cell with two glass windows for the measurement of two-dimensional electric field vector and the other was a Teflon rectangular cell for the measurement of three-dimensional electric field vector.<BR>The He-Ne laser was used for a light source. The negative high voltage pulse was applied to the electrodes which were displaced in nitrobenzene. The intensity of the light transmitted through out the analyzer was measured with a photodiode. The electric field vector was calculated from the intensity of the measured light by the computer.

DOI： 10.5188/jsmerj.5.2_83

J-GLOBAL

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

It is very difficult to measure nonuniform electric field distributions in insulators. The optical measurements of the electric field were investigated in nitrobenzene using the Kerr effect. A sphere-to-sphere electrode or a sphere-to-plane electrode system was used to produce the nonuniform electric field. A rectangular test cell was made of teflon with two glass windows. A He-Ne laser was used for a light source. The intensity of the light transmitted through the cell was measured with a photodiode. The two-dimensional electric field distribution expressed in absolute value was reconstructed by the computed tomography (CT) method. The measured electric fields were compared with the theoretical one and good agreement was obtained. © 1992 The Japan Society of Applied Physics.

DOI： 10.1143/JJAP.31.1901

Scopus

researchmap

researchmap

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：I E E E  

The authors have carried out optical measurements of the field-strength map in a liquid dielectric using the Kerr effect. Since electric lines of force are curved in a nonuniform field, the field strength can be measured on a plane which divides the center axis of two sphere electrodes into two equal parts and is perpendicular to the axis. On this plane, all of the field directions are constant and the field direction is perpendicular to that of transmitted light. The sample liquid was nitrobenzene, which has a Kerr constant of 3.62 × 10-12 (m/V2). The test cell was rectangular and was made of Teflon with two glass windows. An He-Ne laser was used as the light source. The intensity of the light transmitted through the cell was measured with a photodiode. The two-dimensional field strength was calculated by the ART (algebraic reconstruction technique) method. When a voltage pulse of 50 ms and 8 kV was applied to the electrodes, the maximum field strength was 2.9 kV/cm, while the theoretical value was 3.3 kV/cm.

Web of Science

Scopus

researchmap

Event date： 2024.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2024.9

Language：Japanese   Presentation type：Poster presentation  

researchmap

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2024.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2023

researchmap

Event date： 2023

researchmap

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.9

Language：English   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2021.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2020.3

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2019.9

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Event date： 2011.8

Language：Japanese  

researchmap

Event date： 2006.3

Language：Japanese  

researchmap

Event date： 2005.9

Language：Japanese  

Conducting polymers has been usually polymerized on an electrode. Under certain conditions, The polymerized points move from the electrode to a bottom surface of a cell and thus two-dimensional conducting polymer is fabricated on the surface. 2-D conducting polymers sometimes grow from tips of 3-D conducting polymers which grow from the electrode to solvent. Oligomer and/or polymer, which does not attach to film of conducting polymer on the electrode, play important role. It has been investigated the conducting polymer was fabricated on the surface at the conditions that concentrations of oligomer/polymer increase near the bottom surface using needle electrode which does not touch the bottom surface. The transition mechanism to 2-D growth has been discussed.

researchmap

Event date： 2004.9

Language：Japanese  

The learning effect of the network conducting polymer has been investigated to develop a new device. The conductivity of the composite conducting polymer has depended on the signals which passed through the path of the conducting polymer in the solution with dopant. After dropping the droplet of ethanol, the conductivity has changed. The learning effect can add to the network of triple-layer conducting polymer. It has been also investigated that the learning effect works under alternate signals.

researchmap

Event date： 2002.5

Language：Japanese  

Conducting polymers with fractal patterns have been prepared electrochemically under some polymerization conditions. Furthermore these polymers are connected each other by the change of polymerization conditions during the growing process. If the conductivity of the path in the conducting polymer network changes with the amount of the electric charge that flows in the path, neuron-like conducting polymer device can be proposed. Conducting polymer gel has been used to control the conductivity of the path. A simple network of conducting polymer has been prepared to investigate the control of weight of the path.

researchmap

Event date： 2001.9

Language：English  

researchmap

Event date： 2001.9

Language：Japanese  

researchmap

Event date： 2000.9

Language：Japanese  

In order to develop a new device of neuron-like conducting polymer prepared eletrochemically, two methods to control the weight of the path between network conducting polymer have been invesigated : one method uses the third electrode. Another uses the characteristic of the gel of conducting polymer. i Furthermore, A characteristic of an artificially simple network of conducting polymer gel is investigated.

researchmap

Event date： 1996.9

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Poster presentation  

researchmap

Language：Japanese   Presentation type：Poster presentation  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Poster presentation  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese   Presentation type：Oral presentation (general)  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap

Language：Japanese  

researchmap