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398 results on '"Kumada, Akiko"'

3. xEMS: Control Towers of Optimal Energy Flow Management for Smart City Realization

Author

Jie, Bo, Baba, Jumpei, Kumada, Akiko, Biloria, Nimish, Series Editor, Burry, Jane, Editorial Board Member, Choi, Jaz Hee-jeong, Editorial Board Member, Foth, Marcus, Editorial Board Member, Gammons, Tim, Editorial Board Member, Hensel, Michael, Editorial Board Member, Roggema, Rob, Editorial Board Member, Majumdar, Sushobhan, editor, Kandpal, Vinay, editor, and Anthopoulos, Leonidas G., editor

Published
2024
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8. Particle-In-Cell Simulation for Breakdown Initiating Process in Vacuum

Author

Ejiri, Haruki, Kumada, Akiko, Hidaka, Kunihiko, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Liang, Qilian, Series Editor, Martin, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zhang, Junjie James, Series Editor, and Németh, Bálint, editor

Published
2020
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23. Atomistic Modeling of Charge Injection Into Dielectric Polymers

Author

Sato, Masahiro, Kumada, Akiko, and Hidaka, Kunihiko

Abstract

Electrical degradation and electric field distortion in polymers are inherently determined by their charge transfer and charge injection properties. In this contribution, we have proposed a first-principles-based multi-scale modeling approach for describing charge injection into dielectric polymers. First-principles calculations and molecular dynamics (MD) simulations are performed to determine the microscopic physical quantities that enter the non-empirical formula describing charge injection. It is shown that, among the several well-known charge injection models, the disorder-based injection model is relatively appropriate for modeling carrier injection from the electrode into dielectric polymers. From a theoretical point of view, the field emission (FE) and the thermal emission (TE) models are unsuitable for describing charge injection into dielectrics, and the agreement between experimental data and the injection current predicted by these models is most likely accidental. According to the disorder-based injection model, in line with the experimental findings, the simulated injection current increases rapidly at the field above $10^{{2}}$ kV/mm. The computational results indicate that the carriers would be injected from the amorphous region rather than from the crystalline region and that the impurity or interface states play a crucial role in charge injection. Novel non-empirical theoretical models taking into account these mid-gap states are required to describe the injection current into dielectric polymers.

Published
2023
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41. First principles study of hole transport properties in amorphous polyethylene: Effect of bromine doping.

Author

Sato, Masahiro, Kumada, Akiko, and Hidaka, Kunihiko

Subjects
*AMORPHOUS alloys, *POLYETHYLENE, *BROMINE, *OLIGOMERS, *SEMICONDUCTOR doping
Abstract

The effect of bromine (Br 2) doping on the hole transfer properties in amorphous polyethylene (PE) oligomer is studied by utilizing a multi-scale computational approach without adopting any empirical models. The computational method comprises molecular dynamics simulations, quantum chemical calculations, and kinetic Monte Carlo simulations. The electronic structure of the Br 2 /PE oligomer cluster and the ionization energies of Br 2 and PE oligomer showed that no impurity states are introduced in the HOMO-LUMO gap of PE oligomers upon Br 2 doping, i.e., holes tend to hop between PE oligomers instead of residing in Br 2. Nevertheless, owing to the increase of electronic couplings between PE oligomers due to the occupied states of Br 2 , the hole mobility is increased by an order of magnitude with Br 2 doping. In addition, the hole mobility activation energy was decreased upon Br 2 doping, even though the activation energies of hole hopping rates remain the same. The computational results are consistent with experimental observations in literature and imply that the hole mobility in PE is increased by the bridge mediated hole transfer. [ABSTRACT FROM AUTHOR]

Published
2018
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