Search results for: Tatsuo Takada

Items from 1 to 20 out of 31 results

article

An evaluation method of observable charge trap depth for the PEA method and its complementarity with the Q(t) method

Hanwen Ren, Tatsuo Takada, Yasuhiro Tanaka, Qingmin Li

Metrology and Measurement Systems > 2021 > Vol. 28, nr 3 > 565--580

This paper proposes an evaluation method for the observable trap depth range of space charge when using the pulsed electro-acoustic (PEA) method and its complementarity with the current integration charge (Q(t)) method. Based on the measurement process of the PEA method and the hopping conduction principle of space charge, the relationship between the trap depth and the residence time of charge is...

article

Surface trap effects on flashover voltages of epoxy/Al₂O₃ nanocomposites for high voltage insulation

Shihu Yu, Shihang Wang, M. Tariq Nazir, Weiwang Wang, more

Journal of Materials Science: Materials in Electronics > 2019 > 30 > 19 > 18135- 18143

In this paper, surface trap distribution and the affected surface charge transport properties in epoxy/Al₂O₃ nanocomposites were studied to provide theoretical and experimental basis for improving surface flashover performance in vacuum. Four different contents of nano-Al₂O₃ particles were doped into epoxy and different trap distribution of samples was calculated from the surface potential decay method...

article

Influence of oxidation on the dynamics in amorphous ethylene-propylene-diene-monomer copolymer: A molecular dynamics simulation

Weiwang Wang, Yasuhiro Tanaka, Tatsuo Takada, Shinya Iwata, more

Polymer Degradation and Stability > 2018 > 147 > C > 187-196

This work is dedicated to the mechanism underlying the influence of the oxidation on the dynamic and static characteristics of ethylene-propylene-diene monomer (EPDM) copolymer. A molecular dynamics simulation was employed to provide an insight into the effects of oxidation on the micro and macroscopic properties, such as the density and self-diffusion, free volume, glass transition, and chain transition...

article

Trap-controlled charge decay and quantum chemical analysis of charge transfer and trapping in XLPE

Welwang Wang, Tatsuo Takada, Yasuhiro Tanaka, Shengtao Li

IEEE Transactions on Dielectrics and Electrical Insulation > 2017 > 24 > 5 > 3144 - 3153

The present work studies the space charge accumulation and decay in the degassed cross-linked polyethylene (XLPE) by detrapping mechanism and quantum chemical method. Experimentally, significant positive charge packets were observed at room temperature (300 K). Negative charges accumulated strikingly under high temperatures but with a fast decay during depolarization. The estimated bipolar carrier...

article

Computational study on acetophenone in amorphous polyethylene

Shinya Iwata, Hiroaki Uehara, Tatsuo Takada

Journal of Molecular Modeling > 2017 > 23 > 10 > 1-9

Polyethylene (PE) is widely used as an electrical insulating material. Acetophenone (AP) is a major residue in PE and is considered one of the causes of insulation deterioration. However, the physicochemical explanation of the influence of AP is still unknown. Therefore, in the present study, the behavior of AP molecules in amorphous PE was investigated using molecular dynamics (MD) simulations and...

chapter

Space charge analysis and trap evaluation in silicone rubber by density functional study

Weiwang Wang, Yasuhiro Tanaka, Tatsuo Takada, Shengtao Li

2017 International Symposium on Electrical Insulating Materials (ISEIM) > 176 - 179

2017 International Symposium on Electrical Insulating Materials (ISEIM)

This paper presents the fundamental characteristics of the electronic structures of silicone rubber (uncured SR) and cured (crosslinked) SR molecules. Localized states and trapping sites are evaluated by the molecular orbitals (MOs) and the density of state (DOS). The introduction of vinyl groups slightly changes the energy level distribution and introduces the electron-localized states (shallow trapping...

chapter

A study on electric charge behaviors in polymeric materials using “direct current integrated charge method”

Yoitsu Sekiguchi, Tatsuo Takada, Hiroaki Miyake, Yasuhiro Tanaka

2017 International Symposium on Electrical Insulating Materials (ISEIM) > 2 > 691 - 694

2017 International Symposium on Electrical Insulating Materials (ISEIM)

The space charge accumulation in polymeric materials is one of the important behaviors of pre-ageing phenomena in electrical insulations. The Pulsed electro-acoustic (PEA) method is an appropriate method to understand the space charge behavior, but some kind of charges such as charges with high speed are hardly detected by the method. To understand the whole information of charges, that is Q(t) behaviors,...

chapter

Quantum chemical calculations of surfactant having suppression effect on water trees

Hiroaki Uehara, Shinya Iwata, Yasuo Sekii, Tatsuo Takada, more

2017 International Symposium on Electrical Insulating Materials (ISEIM) > 2 > 470 - 473

2017 International Symposium on Electrical Insulating Materials (ISEIM)

Polyethylene (PE) is a hydrophobic polymeric insulating material. It has been found that adding hydrophilic additives can enhance the water tree resistance of PE. On the other hand, a surfactant contains both hydrophobic and hydrophilic groups in its molecular structure. It is considered that a surfactant added to PE surrounds water molecules and stabilizes them. Hence, it is highly plausible that...

chapter

Evaluation of insulating materials during DC voltage charging by DCIC method

Keita Sonoda, Koichi Ota, Shugo Yoshida, Tsuyoshi Tohmine, more

2017 1st International Conference on Electrical Materials and Power Equipment (ICEMPE) > 233 - 238

2017 1st International Conference on Electrical Materials and Power Equipment (ICEMPE)

We have developed a new method “direct current integrated charge (DCIC) method” for evaluating a deterioration of insulating materials in power equipments. The three important dielectric parameters, that is, conductivity, relative permittivity, and accumulated charge amounts are evaluated simultaneously by a relatively simple treatment of the method. Since the total amount of charges is found as an...

chapter

Study on conduction current and space charge accumulation simultaneously in Ethylene Propylene Diene Monomer film

Weiwang Wang, Yasuhiro Tanaka, Toshiyuki Fujitomi, Tatsuo Takada, more

2017 1st International Conference on Electrical Materials and Power Equipment (ICEMPE) > 464 - 467

2017 1st International Conference on Electrical Materials and Power Equipment (ICEMPE)

This paper investigates the space charge distribution and external current performance of Ethylene Propylene Diene Monomer (EPDM) film simultaneously by an improved integrated PEA system. Through switching the space charge and current measurement circuits, the space charge and external current were detected alternately during the electric field of 60 kV/mm and 80 kV/mm. Small amounts of homocharges...

article

New diagnostic method of electrical insulation properties based on current integration

Tatsuo Takada, Toshiyuki Fujitomi, Takuma Mori, Tomoyuki Iwata, more

IEEE Transactions on Dielectrics and Electrical Insulation > 2017 > 24 > 4 > 2549 - 2558

We developed a compact system for evaluating the deterioration of insulating materials used in high-voltage dc power apparatuses. The developed system can be used for simultaneous determination of three basic parameters important for evaluating the deterioration of high-voltage insulation materials, i.e., conductivity, dielectric constant, and charge accumulation. Charge accumulation, which is detrimental...

article

Space charge mechanism of polyethylene and polytetrafluoroethylene by electrode/dielectrics interface study using quantum chemical method

Welwang Wang, Tatsuo Takada, Yasuhiro Tanaka, Shengtao Li

IEEE Transactions on Dielectrics and Electrical Insulation > 2017 > 24 > 4 > 2599 - 2606

This work studies the space charge mechanisms of PE and PTFE by involving the combination of electronic structures and charge transfer processes at the interfaces of electrode/dielectrics. Experimentally, significant positive charge packets were observed in LDPE when subjected to a high electric stress. However, slight charge accumulations (mainly homo-charges) were observed inside polytetrafluoroethylene...

article

Properties of Space Charge Distributions and Conduction Current in XLPE and LDPE under DC High Electric Field

TSUYOSHI KATO, RYO ONOZAWA, HIROAKI MIYAKE, YASUHIRO TANAKA, more

Electrical Engineering in Japan > 198 > 3 > 19 - 26

Space charge behavior and conduction current in polyethylene under dc stress were investigated. One of the reasons for the different breakdown property in cross‐linked polyethylene (XLPE) from that in low‐density polyethylene (LDPE) may be based on the existence of cross‐linking by‐products in XLPE. Furthermore, a thermal history in cross‐linking process for XLPE may also cause of the difference....

chapter

An electric stress pulse technique for the measurement of charges in a plastic plate irradiated by an electron beam

Tatsuo Takada, Takashi Maeno, Hidehumi Kushibe

1985 5th International Symposium on Electrets (ISE 5) > 450 - 455

1985 5th International Symposium on Electrets (ISE 5)

The determination of the amount and distribution profile of charges in insulators has been studied by various methods, some of them utilizing thermal, mechanical and electrical stimulations. A new method incorporating pulse electrical stimulations and pulse acoustic detection is reported here, along with the preliminary results of the measurement of the amount and distribution profile of charges in...

chapter

Study on accumulation mechanism of space charge in covering insulating material for motor windings

Kaoru Takizawa, Tomoki Suetsugu, Tomoyuki Iwata, Hiroaki Miyake, more

2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP) > 804 - 807

2014 IEEE Conference on Electrical Insulation and Dielectric Phenomena - (CEIDP 2014)

In this study, we examined the accumulation mechanism of the space charge in a covering insulating material of motor windings under high voltage based on measurement results of space charge distributions. In these days, the inverter-fed motor drive using pulse width modulation control is applied to many electric devices for industrial machinery, automotive, railway cars and so on. For further improvement...

chapter

Quantum chemical calculation studies on interface charge transfer between electrode and polyethylene under electrical stress

Tatsuo Takada, Hiroaki Miyake, Yasuhiro Tanaka, Masafumi Yoshida

Proceedings of 2014 International Symposium on Electrical Insulating Materials > 97 - 100

2014 International Symposium on Electrical Insulating Materials (ISEIM)

The mechanism of charge injection, the interface charge transfer between LDPE and SC (semi-conductive) or Al electrode, was investigated by using the density function theory (DFT) of Gaussian 09. The electric dipole layer between electrode (Al or SC) and LDPE is created after contact because Fermi levels between the LDPE and electrodes are difference. As the barrier height of hole injection (ϕ_Bh=1...

chapter

Characteristics of space charge behavior and conduction current in xlpe and annealed polyethylene under high DC stress

Tsuyoshi Kato, Ryo Onozawa, Hiroaki Miyake, Yasuhiro Tanaka, more

Proceedings of 2014 International Symposium on Electrical Insulating Materials > 370 - 373

2014 International Symposium on Electrical Insulating Materials (ISEIM)

Space charge behavior and conduction current in XLPE and annealed LDPE under DC high electric field were investigated. One of the reasons for the different breakdown property in XLPE from that in LDPE may be based on the existence of cross-linking by-products in XLPE. Furthermore, a thermal history in cross-linking process for XLPE under high temperature may also cause of the difference. It is generally...

chapter

Space charge accumulation and degradation in electron beam irradiated dielectrics for spacecraft

Yutaka Kikuchi, Shinji Kashiwagi, Tatsuo Takada, Hiroaki Miyake, more

2013 IEEE International Conference on Solid Dielectrics (ICSD) > 744 - 747

2013 IEEE International Conference on Solid Dielectrics (ICSD)

Effect of electron beam irradiation on dielectric properties in various insulating materials for spacecraft is investigated using PEA (Pulsed Electro-Acoustic) method. In space environment, spacecraft is exposed to plasma or radioactive-rays. In such condition, multilayer insulating materials covering the spacecraft are charged up. Sometimes the charge accumulation causes to the serious damage to...

chapter

Space charge accumulation in coating materials for motor windings under DC high voltage

Motohiro Negishi, Kentaro Akada, Kaoru Takizawa, Hiroaki Miyake, more

2012 IEEE International Conference on Condition Monitoring and Diagnosis > 122 - 125

2012 IEEE International Conference on Condition Monitoring and Diagnosis (CMD)

Recently, the switching frequency of motors for automotive and railway cars are increased according with the innovation of power semiconductor technology. When the switching speed is increased, so called “inverter surge voltage” is increased, then the coating insulating materials are degraded due to the high voltage phenomena like partial discharge, dielectric heating and space charge accumulation...

article

A case of meningitis due to Neisseria subflava after ventriculostomy

Daisuke Wakui, Goro Nagashima, Yoshinobu Otsuka, Tatsuo Takada, more

Journal of Infection and Chemotherapy > 2012 > 18 > 1 > 115-118

Surgical site infection (SSI) is an emerging problem in all fields of surgery, as well as in neurosurgery, with numerous strategies against SSI initiated in many countries. In this report, we describe a case of SSI caused by Neisseria subflava a month after ventriculostomy placement for acute hydrocephalus. A 53-year old man was referred to our hospital, and was diagnosed with a thalamic hemorrhage...

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CONDUCTIVITY (4)
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Search results for: Tatsuo Takada

An evaluation method of observable charge trap depth for the PEA method and its complementarity with the Q(t) method

Surface trap effects on flashover voltages of epoxy/Al₂O₃ nanocomposites for high voltage insulation

Influence of oxidation on the dynamics in amorphous ethylene-propylene-diene-monomer copolymer: A molecular dynamics simulation

Trap-controlled charge decay and quantum chemical analysis of charge transfer and trapping in XLPE

Computational study on acetophenone in amorphous polyethylene

Space charge analysis and trap evaluation in silicone rubber by density functional study

A study on electric charge behaviors in polymeric materials using “direct current integrated charge method”

Quantum chemical calculations of surfactant having suppression effect on water trees

Evaluation of insulating materials during DC voltage charging by DCIC method

Study on conduction current and space charge accumulation simultaneously in Ethylene Propylene Diene Monomer film

New diagnostic method of electrical insulation properties based on current integration

Space charge mechanism of polyethylene and polytetrafluoroethylene by electrode/dielectrics interface study using quantum chemical method

Properties of Space Charge Distributions and Conduction Current in XLPE and LDPE under DC High Electric Field

An electric stress pulse technique for the measurement of charges in a plastic plate irradiated by an electron beam

Study on accumulation mechanism of space charge in covering insulating material for motor windings

Quantum chemical calculation studies on interface charge transfer between electrode and polyethylene under electrical stress

Characteristics of space charge behavior and conduction current in xlpe and annealed polyethylene under high DC stress

Space charge accumulation and degradation in electron beam irradiated dielectrics for spacecraft

Space charge accumulation in coating materials for motor windings under DC high voltage

A case of meningitis due to Neisseria subflava after ventriculostomy

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