Details of a Researcher - Isakari, Hiroshi

Isakari, Hiroshi

写真a

Affiliation: Faculty of Science and Technology, Department of System Design Engineering (Yagami)

Position: Associate Professor

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Career 【 Display / hide 】

2010.04

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2012.03

日本学術振興会特別研究員(DC2)
2012.04

Kyoto University, Graduate School of Informatics, 特定研究員
2012.05

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2021.03

Nagoya University, Graduate School of Engineering, Assistant Professor
2021.04

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2023.03

Keio University, Faculty of Science and Technology, Department of System Design Engineering, Assistant Professor
2023.04

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Present

Keio University, Department of System Design Engineering, Faculty of Science and Technology, Associate Professor

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Academic Background 【 Display / hide 】

2003.04

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2007.03

Kyoto University, Faculty of Engineering, Undergraduate School of Global Engineering
2007.04

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2009.03

Kyoto University, Graduate School of Engineering, Department of Civil and Earth Resources Engineering
2009.04

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2012.03

Kyoto University, Graduate School of Engineering, Department of Civil and Earth Resources Engineering

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Research Areas 【 Display / hide 】

Natural Science / Applied mathematics and statistics
Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Design engineering
Informatics / Computational science

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Papers 【 Display / hide 】

BEM-based fast frequency sweep for acoustic scattering by periodic slab

Yuta Honshuku, Hiroshi Isakari

Journal of Computational Physics (Elsevier BV) 509 113046 - 113046 2024.07

Last author, Corresponding author, Accepted, ISSN 0021-9991
- Access to Document (DOI)
A Burton–Miller-type boundary element method based on a hybrid integral representation and its application to cavity scattering

Riku Toshimitsu, Hiroshi Isakari

Engineering Analysis with Boundary Elements (Elsevier BV) 158 303 - 312 2024.01

Last author, Corresponding author, Accepted, ISSN 0955-7997
- Access to Document (DOI)
A topology optimisation of acoustic devices based on the frequency response estimation with the Padé approximation

Yuta Honshuku, Hiroshi Isakari

Applied Mathematical Modelling (Elsevier BV) 110 819 - 840 2022.10

Last author, Corresponding author, ISSN 0307-904X
- Access to Document (DOI)
A topology optimization of open acoustic waveguides based on a scattering matrix method

Kei Matsushima, Hiroshi Isakari, Toru Takahashi, Toshiro Matsumoto

Wave Motion (Elsevier BV) 113 102987 - 102987 2022.08

Accepted, ISSN 0165-2125

　View Summary

This study presents a topology optimization scheme for realizing a bound state in the continuum along an open acoustic waveguide comprising a periodic array of elastic materials. First, we formulate the periodic problem as a system of linear algebraic equations using a scattering matrix associated with a single unit structure of the waveguide. The scattering matrix is numerically constructed using the boundary element method. Subsequently, we employ the Sakurai–Sugiura method to determine resonant frequencies and the Floquet wavenumbers by solving a nonlinear eigenvalue problem for the linear system. We design the shape and topology of the unit elastic material such that the periodic structure has a real resonant wavenumber at a given frequency by minimizing the imaginary part of the resonant wavenumber. The proposed topology optimization scheme is based on a level-set method with a novel topological derivative. We demonstrate a numerical example of the proposed topology optimization and show that it realizes a bound state in the continuum through some numerical experiments.
- Access to Document (DOI)
A robust topology optimisation for wideband structures in acoustic–elastodynamic coupled fields

Jincheng Qin, Hiroshi Isakari, Toru Takahashi, Toshiro Matsumoto

Engineering Analysis with Boundary Elements (Elsevier BV) 140 544 - 561 2022.07

Corresponding author, Accepted, ISSN 0955-7997

　View Summary

On designing wave devices, perturbation in excitation frequency might give rise to serious degradation in the device performance. To address this issue, in our previous research, a robust topology optimisation (RTO) for acoustically rigid structures has been proposed. In the RTO, the angular frequency of the incident wave is assumed to be a stochastic variable subject to the normal distribution, and the uncertainty in the response is modelled using high-order Taylor's expansion. Our high-order RTO has successfully broadened the working bandwidth of acoustic devices. In this study, we extend our RTO to design viscoelastic structures involving acoustic–elastodynamic coupled waves in two dimensions. This enables us to deal with materials having more realistic acoustic properties than the rigid one. However, the computation of high-order derivatives for the coupled problem can result in low efficiency, which becomes the main difficulty in realising desirable optimisation for large scale problems. We thus propose an acceleration of our boundary element method (BEM) by employing the H-matrix method and the fast multipole method (FMM) and install the new BEM into the RTO. The proposed RTO is numerically exemplified by several acoustic designs. The results show that the proposed method can find the shape of wideband acoustic devices within a feasible computational time.
- Access to Document (DOI)

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

High-order frequency derivatives of wave scattered field in infinite domains and their engineering applications

2023.04

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2027.03

基盤研究(B), Principal investigator
グリーン関数の求まらない形状の領域における境界要素法

2021.07

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2023.03

MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Challenging Research (Exploratory), Principal investigator
Multi-physics topology optimisation in periodic domain for design of micro phononic crystals

2017.04

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2021.03

Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), Grant-in-Aid for Young Scientists (B), No Setting
Fast direct solvers for the boundary element method in 3D and their applications to optimal design problems

2014.04

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2016.03

Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B), Isakari Hiroshi, Grant-in-Aid for Young Scientists (B), No Setting
動弾性学の周期境界値問題における高速多重極境界積分方程式法

2010

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2011

日本学術振興会, 科学研究費助成事業特別研究員奨励費, 特別研究員奨励費, No Setting