九州大学 研究者情報
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基本情報 研究活動 教育活動 社会活動
瀬片 純市(せがた じゅんいち) データ更新日:2024.04.01



主な研究テーマ
非線形分散型偏微分方程式の解の長時間挙動についての研究
キーワード:偏微分方程式, 調和解析
2019.04~2031.03.
研究業績
主要原著論文
1. Satoshi Masaki, Jun-ichi Segata, and Kota Uriya, On asymptotic behavior of solutions to cubic nonlinear Klein-Gordon systems in one space dimension, Transactions of the American Mathematical Society, Ser. B, 9, 517-563, 2022.06.
2. Jean-Claude Saut and Jun-ichi Segata, Long range scattering for the nonlinear Schrodinger equation with higher order anisotropic dispersion in two dimensions, Journal of Mathematical Analysis and Applications, 483, 2020.03, This paper is concerned with long time behavior of solution to the nonlinear Schrödinger equation with higher order anisotropic dispersion (4NLS). We prove the long range scattering for (4NLS) with the quadratic nonlinearity in two dimensions. More precisely, We construct a solution to (4NLS) which converges to prescribed asymptotic profile as t tends to infinity, where asymptotic profile is given by the leading term of the solution to the linearized equation of (4NLS) with a logarithmic phase correction..
3. Satoshi Masaki, Jason Murphy, Jun-ichi Segata, Modified scattering for the 1d cubic NLS with a repulsive delta potential, International Mathematics Research Notices, 2019, 24, 7577-7603, 2019.12, We consider the initial-value problem for the one dimensional cubic nonlinear Schr"odinger equation with a repulsive delta potential. We prove that small initial data in a weighted Sobolev space lead to global solutions that exhibit modified scattering..
4. Satoshi Masaki, Jun-ichi Segata and Kota Uriya, Long range scattering for the complex-valued Klein-Gordon equation with quadratic nonlinearity in two dimensions, Journal de Mathematiques Pures et Appliquees., 139, 177-203, 2020.02.
5. Satoshi Masaki, Jun-ichi Segata, Refinement of Strichartz estimate for Airy equation in non-diagonal case and its application, SIAM Journal on Mathematical Analysis, 10.1137/17M1153893, 50, 3, 2839-2866, 2018.04, In this paper, we give an improvement of non-diagonal Strichartz estimates for Airy equation by using a Morrey type space.
As its applications, we prove the small data scattering and the existence of special non-scattering solutions, which are minimal in a suitable sense, to the mass-subcritical generalized Korteweg-de Vries equation. Especially, a use of the refined non-diagonal estimate removes several technical restrictions on the previous work about the existence of the special
non-scattering solution..
6. Satoshi Masaki, Jun-ichi Segata, Modified scattering for the quadratic nonlinear Klein-Gordon equation in two dimensions, Transactions of the American Mathematical Society, 10.1090/tran/7262, 370, 11, 8155-8170, 2018.04, In this paper, we consider the long time behavior of solution to the quadratic gauge invariant nonlinear Klein-Gordon equation in two space dimensions. For a given asymptotic profile, we construct a solution to this equation which converges to given asymptotic profile as t goes infinity. Here the asymptotic profile is given by the leading term of the solution to the linear Klein-Gordon equation with a logarithmic phase correction. Construction of a suitable approximate solution is based on Fourier series expansion of the nonlinearity..
7. Satoshi Masaki, Jun-ichi Segata, Existence of a minimal non-scattering solution to the mass sub-critical generalized Korteweg-de Vries equation, Annales de l'Institut Henri Poincar'e/Analyse non lin'eaire, 10.1016/j.anihpc.2017.04.003, 35, 2, 283-326, 2018.04, In this article, we prove the existence of a non-scattering solution, which is minimal in some sense, to the mass-subcritical
generalized Korteweg-de Vries equation in the scale critical Fourier Lebesgue space. We construct this solution by a concentration compactness argument. Then, key ingredients are a linear profile decomposition result adopted to Fourier Lebesgue space-framework and approximation of solutions to the generalized KdV equation which involves rapid linear oscillation by means of solutions to the nonlinear Schr"odinger equation..
8. Yung-Fu Fang, Chi-Kun Lin, Jun-ichi Segata, The fourth order nonlinear Schr"odinger limit for quantum Zakharov system, Zeitschrift f"ur angewandte Mathematik und Physik, ZAMP - Journal of Applied Mathematics and Physics, 10.1007/s00033-016-0740-1, 67, 6, article number 145, 2016.04, This paper is concerned with the quantum Zakharov system. We prove that when the ionic speed of sound goes to infinity, the solution to the fourth order Schr"odinger part of the quantum Zakharov system converges to the solution to quantum modified nonlinear Schr"odinger eqaution..
9. Satoshi Masaki, Jun-ichi Segata, On well-posedness of generalized Korteweg-de Vries equation in scale critical hat Lr space, Analysis & PDE, 10.2140/apde.2016.9.699, 9, 3, 699-725, 2016.04, The purpose of this paper is to study local and global well-posedness of initial value problem for the generalized Korteweg-de Vries equation in Fourier Lebesgue space. We show (large data) local well-posedness, small data global well-posedness, and small data scattering for generalized KdV equation in the scale critical Fourier Lebesgue space. A key ingredient is a Stein-Tomas type inequality for the Airy equation, which generalizes usual Strichartz' estimates for Fourier Lebesgue space-framework..
10. Jun-ichi Segata, Final state problem for the cubic nonlinear Schr"odinger equation with repulsive delta potential, Communications in Partial Differential Equations, 10.1080/03605302.2014.930753, 40, 2, 309-328, 2015.04, We consider the asymptotic behavior in time of solutions to the cubic nonlinear Schr"odinger equation with repulsive delta potential. We shall prove that for a given small asymptotic profile, there exists a solution to this equation which converges to given asymptotic profile as t to infinity. To show this result we exploit the distorted Fourier transform associated to the Schr"odinger equation with delta potential..
11. Jun-ichi Segata, Refined energy inequality with application to well-posedness for the fourth order nonlinear Schr"odinger type equation on torus, Journal of Differential Equations, 10.1016/j.jde.2012.02.016, 252, 11, 5994-6011, 2012.04, We consider the time local and global well-posedness for the fourth order nonlinear Schr"odinger type equation on the torus. The nonlinear term contains the derivatives of unknown function and this prevents us to apply the classical energy method. To overcome this difficulty, we introduce the modified energy and derive an a priori estimate for the solution to this equation..
12. Masaya Maeda, Jun-ichi Segata, Existence and Stability of standing waves of fourth order nonlinear Schr"odinger type equation related to vortex filament, Funkcialaj Ekvacioj, 10.1619/fesi.54.1, 54, 1, 1-14, 2011.04, In this paper, we study the fourth order nonlinear Schr"odinger type equation which is a generalization of the Fukumoto-Moffatt model that arises in the context of the motion of a vortex filament. Firstly, we mention the existence of standing wave solution and the conserved quantities. We next investigate the case that the equation is completely integrable and show that the standing wave is orbitally stable in Sobolev spaces..
13. Jun-ichi Segata, On asymptotic behavior of solutions to Korteweg-de type equations related to vortex filament with axial flow, Journal of Differential Equations, 10.1016/j.jde.2008.03.031, 245, 2, 281-306, 2008.04, We study the global existence and asymptotic behavior in time of solutions to the Korteweg-de Vries type equation called as ``Hirota" equation. This equation is a mixture of cubic nonlinear Schr"odinger equation and modified Korteweg-de Vries equation. We show the unique existence of the solution for this equation which tends to the given modified free profile by using the two asymptotic formulae for some oscillatory integrals..
14. Jun-ichi Segata, Modified wave operators for the fourth-order non-linear Schr"odinger-type equation with cubic non-linearity, Mathematical Methods in the Applied Sciences, 10.1002/mma.751, 29, 15, 1785-1800, 2006.04, We consider the scattering problem for the fourth order nonlinear Schr"odinger type equation. We show the existence of the modified wave operators for this equation by imposing the mean zero condition for the final data..
15. Naoyasu Kita, Jun-ichi Segata, Time local well-posedness for the Benjamin-Ono equation with large initial data, Publications of the Research Institute for Mathematical Sciences, Kyoto University, 10.2977/prims/1166642062, 42, 1, 143-171, 2006.01, This paper studies the time local well-posedness of the solution to the Benjamin-Ono equation. Our aim is to remove smallness condition on the initial data which was imposed in Kenig-Ponce-Vega's work..
16. Jun-ichi Segata, Remark on well-posedness for the fourth order nonlinear Schr"odinger type equation, Proceedings of the American Mathematical Society, 10.1090/S0002-9939-04-07620-8, 132, 12, 3559-3568, 2004.12, We consider the initial value problem for the fourth order nonlinear Schr"odinger type equation related to the theory of vortex filament. In this paper we prove the time local well-posedness for this equation in the Sobolev space..
主要学会発表等
1. 瀬片 純市, デルタポテンシャルをもつ非線形シュレディンガー方程式の解の長時間挙動, 日本数学会2020年度秋季総合分科会, 2020.09, 本講演では、デルタポテンシャルをもつ非線形シュレディンガー方程式の解の長時間挙動について、眞崎聡氏(大阪大)、Jason Murphy氏(ミズーリ工科大)との共同研究により得られた成果(散乱問題及びソリトンの漸近安定性)について紹介した。.
2. Jun-ichi Segata, Modified scattering for the complex valued nonlinear Klein-Gordon equation, Colloquia at Department of Mathematics and Statistics, Missouri University of Science and Technology, 2019.12.
3. Jun-ichi Segata, Modified scattering for the 1d cubic NLS with a repulsive delta potential, The 12th bi-annual Conference on Dynamical Systems, Differential Equations and Applications, 2018.07, We consider the initial value problem for the cubic nonlinear Schr"odinger equation (NLS) with a repulsive delta potential in one space dimension. Our goal is to describe the long-time decay and asymptotics of small solutions to (NLS). From the linear scattering theory, we expect that (NLS) will not scatter to the solution to the linear equation. We prove that if the initial data is sufficiently small in a weighted Sobolev space, then there exists a unique global solution to (NLS) that exhibits modified scattering..
4. Jun-ichi Segata, Refinement of Strichartz estimates for Airy equation in non-diagonal case and application, RIMS workshop Harmonic Analysis and Nonlinear Partial Differential Equations, 2018.06.
5. Jun-ichi Segata, Modified scattering for the 1d cubic NLS with a repulsive delta potential, Taiwan-Japan Workshop on Dispersion and Nonlinear Waves, 2018.06.
6. Jun-ichi Segata, Modified scattering for the Klein-Gordon equation with the critical nonlinearity in two and three dimensions, RIMS 研究集会, Nonlinear Wave and Dispersive Equations, 2017.08.
7. Jun-ichi Segata, Modified scattering for the Klein-Gordon equation with critical nonlinearity in two and three dimensions, Nonlinear PDE for Future Applications - Hyperbolic and Dispersive PDE -, 2017.07.
8. Jun-ichi Segata, Existence of a minimal non-scattering solutions to the mass-subcritical generalized Korteweg-de Vries equation, RIMS研究集会, 偏微分方程式の解の形状解析, 2017.06.
9. Jun-ichi Segata, Scattering problem for the generalized Korteweg-de Vries equation, PDE/Applied seminar at UCSB, 2017.03.
10. Jun-ichi Segata, Scattering problem for the generalized Korteweg‐de Vries equation, 2016 Taiwan-Japan Workshop on Dispersion, Navier Stokes, Kinetic, and Inverse Problems, 2016.12.
11. Jun-ichi Segata, Scattering problem for the generalized Korteweg-de Vries equation, Colloquium at Fudan University, 2016.12.
12. Jun-ichi Segata, Refinement of Strichartz estimates for Airy equation and application, RIMS研究集会, 保存則と保存則をもつ偏微分方程式に対する解の正則性,特異性および長時間挙動の研究, 2016.06.
13. Jun-ichi Segata, Well-posedness for the fourth order nonlinear Schr"odinger type equation and orbital stability of standing waves, Math Colloquium at National Cheng Kung University, 2015.06.
14. Jun-ichi Segata, The higher order nonlinear dispersive equation related to the motion of vortex filament, PDE/Applied seminar at UCSB, 2014.04.
学会活動
所属学会名
日本数学会
学協会役員等への就任
2013.03~2014.02, 日本数学会, 地方区代議員.
学会大会・会議・シンポジウム等における役割
2023.11.07~2023.11.10, Critical Phenomena in Nonlinear Partial Differential Equations, Harmonic Analysis, and Functional Inequalities, 実行委員.
学会誌・雑誌・著書の編集への参加状況
2019.04, Kyushu Journal of Mathematics, 国際, 編集委員.
2021.03~2022.02, 数学通信, 国内, 編集委員.
学術論文等の審査
年度 外国語雑誌査読論文数 日本語雑誌査読論文数 国際会議録査読論文数 国内会議録査読論文数 合計
2023年度
2022年度 10  10 
2021年度
2020年度 10 
2019年度 10 
2018年度
2017年度
2016年度
その他の研究活動
海外渡航状況, 海外での教育研究歴
Universit'e de Paris-Sud, Orsay, France, 2015.01~2015.03.
University of California, Santa Barbara, UnitedStatesofAmerica, 2014.03~2014.10.
University of Cergy-Pontoise, France, 2011.05~2011.09.
外国人研究者等の受入れ状況
2022.10~2023.04, 1ヶ月以上, Department of Mathematical Sciences, Faculty of Applied Sciences, Wayamba University of Sri Lanka, SriLanka, 日本学術振興会.
受賞
福原賞, 日本数学会函数方程式論分科会, 2016.12.
建部賢弘奨励賞, 日本数学会, 2007.09.
研究資金
科学研究費補助金の採択状況(文部科学省、日本学術振興会)
2021年度~2023年度, 挑戦的研究(萌芽), 代表, ネットワーク上の非線形シュレディンガー方程式の解析.
2021年度~2024年度, 基盤研究(B), 代表, 質量劣臨界非線項を持つ分散型偏微分方程式の解の大域解析.
2020年度~2023年度, 基盤研究(A), 分担, 準線形双曲-放物型保存則系における時空間非一様ダイ ナミクスの数学解析の新展開.
2019年度~2023年度, 基盤研究(S), 分担, 臨界型非線形数理モデルにおける高次数理解析法の創造.
2017年度~2020年度, 基盤研究(B), 代表, 分散性を伴う非線形偏微分方程式の解の長時間挙動の解析.
2013年度~2016年度, 若手研究(A), 代表, 非線形分散型方程式に対する分散波, 孤立波およびそれらの相互作用の解析.
2009年度~2012年度, 若手研究(B), 代表, 非線形分散型方程式の解の長時間挙動と特異極限について.
2007年度~2008年度, 若手研究(スタートアップ), 代表, 非線形分散型方程式の解の長時間挙動について.
2004年度~2005年度, 特別研究員奨励費, 代表, 流体と水面波を記述する非線形偏微分方程式の適切性と解の挙動について.
競争的資金(受託研究を含む)の採択状況
2012年度~2013年度, 住友財団基礎科学研究助成, 代表, 非線形分散型方程式の分散波と孤立波の相互作用の解析.

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