Researcher basic information

• Doctor of Informatics, Kyoto University

• https://researchmap.jp/read0133008?lang=en

• https://orcid.org/0000-0001-6882-9200
• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=200901087140936495

• 40432215

• https://orcid.org/0000-0001-6882-9200

• 200901087140936495

• Computer simulation
• Numerical scheme
• High performance Computing
• Plasma science
• Space science
• Electromagnetic fields

• Informatics, High performance computing, High-performance Computing
• Informatics, Computational science, Computer Simulation
• Natural Science, Space and planetary sciences, Space Plasma
• Energy Engineering, Fundamental plasma, Plasma Physics

• Master's degree program, Graduate School of Information Science and Technology
• Doctoral (PhD) degree program, Graduate School of Information Science and Technology

Research activity information

• Nov. 2023, Division of Plasma Physics, Association of Asia Pacific Physical Societies, 7th Asia-Pacific Conference on Plasma Physics (AAPPS-DPP2023) Poster Prize
  Reduction of Anisotropy in Numerical Dispersion in the Explicit Finite-Difference Time-Domain Method with Laplacian
  H. Sekido;T. Umeda;Y. Miyoshi
• 16 Nov. 2018, Division of Plasma Physics, Association of Asia Pacific Physical Societies, 2nd Asia-Pacific Conference on Plasma Physics (AAPPS-DPP2018) Poster Prize
  Non-MHD effects in the nonlinear development of the MHD-scale Rayleigh-Taylor instability
  T. Umeda;Y. Wada, International academic award
• 15 Apr. 2015, 文部科学省, 科学技術分野の文部科学大臣表彰 若手科学者賞
  先端的宇宙プラズマ計算機シミュレーション手法の研究
  Japan
• 22 Oct. 2012, 地球電磁気・地球惑星圏学会, 大林奨励賞
  計算機シミュレーション手法の開発とその宇宙プラズマ現象への応用
  International society, Japan
• 29 Nov. 2008, Frontiers in Computational Science 2008 Program Committee, Best Presentations Award for International Conference of Frontiers in Computational Science 2008 Grant Prix
  Vlasov code simulation of GEM reconnection challenge
  K. Togano;T. Umeda;T. Ogino, International academic award, Japan
• 23 Oct. 2005, International Union of Radio Science, International Union of Radio Science Young Scientist Award
  International academic award

• Generation of normal distributions revisited
  Takayuki Umeda
  Computational Statistics, Springer Science and Business Media LLC, 23 Feb. 2024, [Peer-reviewed], [Lead author]
  English, Scientific journal, Abstract
  
  Normally distributed random numbers are commonly used in scientific computing in various fields. It is important to generate a set of random numbers as close to a normal distribution as possible for reducing initial fluctuations. Two types of samples from a uniform distribution are examined as source samples for inverse transform sampling methods. Three types of inverse transform sampling methods with new approximations of inverse cumulative distribution functions are also discussed for converting uniformly distributed source samples to normally distributed samples., 40535275
• Relaxation of the Courant Condition in the Explicit Finite-Difference Time-Domain(2,6) Method with Third- and Fifth-degree Differential Terms
  Harune Sekido; Takayuki Umeda
  Progress In Electromagnetics Research M, 123, 83, 93, The Electromagnetics Academy, 23 Jan. 2024, [Peer-reviewed]
  English, Scientific journal, 40535275
• A novel high accuracy finite-difference time-domain method
  Harune Sekido; Takayuki Umeda
  Earth, Planets and Space, 76, 1, Springer Science and Business Media LLC, 05 Jan. 2024, [Peer-reviewed]
  English, Scientific journal, 40535275
• Advanced numerical techniques for time integration of relativistic equations of motion for charged particles
  Takayuki Umeda; Riku Ozaki
  Earth, Planets and Space, 75, 1, Springer Science and Business Media LLC, 10 Oct. 2023, [Peer-reviewed], [Lead author]
  English, Scientific journal, 40535275
• New Aspects of Energy Conversion in Magnetic Island Dynamics: Particle-in-cell Simulation of Multiple Island Coalescence and MMS Observations
  W.-L. Teh; T. K. M. Nakamura; S. Zenitani; T. Umeda; R. Nakamura
  The Astrophysical Journal, 947, 1, 4, 4, American Astronomical Society, 01 Apr. 2023, [Peer-reviewed]
  English, Scientific journal
• Relaxation of the Courant Condition in the Explicit Finite-Difference Time-Domain Method With Higher-Degree Differential Terms
  Harune Sekido; Takayuki Umeda
  IEEE Transactions on Antennas and Propagation, 71, 2, 1630, 1639, Institute of Electrical and Electronics Engineers (IEEE), Feb. 2023, [Peer-reviewed]
  English, Scientific journal, 40535275
• Spatial and time scaling of coalescing multiple magnetic islands
  T. K. M. Nakamura; W.-L. Teh; S. Zenitani; T. Umeda; M. Oka; H. Hasegawa; A. M. Veronig; R. Nakamura
  Physics of Plasmas, 30, 2, AIP Publishing, 01 Feb. 2023, [Peer-reviewed]
  English, Scientific journal
• A new integrator for relativistic E-cross-B motion of charged particles
  Takayuki Umeda
  Journal of Computational Physics, 472, 111694, 111694, Elsevier BV, Jan. 2023, [Peer-reviewed], [Lead author]
  English, Scientific journal, 40535275
• Multicolor reordering for computing moments in particle-in-cell plasma simulations
  Takayuki Umeda
  Computer Physics Communications, 281, 108499, 108499, Elsevier BV, Dec. 2022, [Peer-reviewed], [Lead author]
  English, Scientific journal, 40535275
• High-power laser experiment forming a supercritical collisionless shock in a magnetized uniform plasma at rest
  R. Yamazaki; S. Matsukiyo; T. Morita; S. J. Tanaka; T. Umeda; K. Aihara; M. Edamoto; S. Egashira; R. Hatsuyama; T. Higuchi; T. Hihara; Y. Horie; M. Hoshino; A. Ishii; N. Ishizaka; Y. Itadani; T. Izumi; S. Kambayashi; S. Kakuchi; N. Katsuki; R. Kawamura; Y. Kawamura; S. Kisaka; T. Kojima; A. Konuma; R. Kumar; T. Minami; I. Miyata; T. Moritaka; Y. Murakami; K. Nagashima; Y. Nakagawa; T. Nishimoto; Y. Nishioka; Y. Ohira; N. Ohnishi; M. Ota; N. Ozaki; T. Sano; K. Sakai; S. Sei; J. Shiota; Y. Shoji; K. Sugiyama; D. Suzuki; M. Takagi; H. Toda; S. Tomita; S. Tomiya; H. Yoneda; T. Takezaki; K. Tomita; Y. Kuramitsu; Y. Sakawa
  Physical Review E, 105, 2, American Physical Society (APS), 11 Feb. 2022, [Peer-reviewed]
  English, Scientific journal
• Multi-scale evolution of Kelvin–Helmholtz waves at the Earth's magnetopause during southward IMF periods
  T. K. M. Nakamura; K. A. Blasl; H. Hasegawa; T. Umeda; Y.-H. Liu; S. A. Peery; F. Plaschke; R. Nakamura; J. C. Holmes; J. E. Stawarz; W. D. Nystrom
  Physics of Plasmas, 29, 1, AIP Publishing, 01 Jan. 2022, [Peer-reviewed]
  English, Scientific journal
• Paradigm Shift in Program Structure of Particle-in-Cell Simulations
  Takayuki Umeda
  Parallel Computing: Technology Trends, Advances in Parallel Computing, 36, 455, 464, IOS Press, 20 Mar. 2020, [Peer-reviewed]
  English, International conference proceedings, 40535275
• Evaluating higher moments in the transverse Kelvin–Helmholtz instability by full kinetic simulation
  Takayuki Umeda
  Physics of Plasmas, 27, 3, AIP Publishing, 01 Mar. 2020, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Stability of Contact Discontinuities in Electrostatic Hybrid- and Full-Vlasov Simulations
  Naru TSUJINE; Takayuki HARUKI; Takayuki UMEDA; Yasuhiro NARIYUKI; Masahiro SATO
  Plasma and Fusion Research, 15, 1401002, 1401002, Japan Society of Plasma Science and Nuclear Fusion Research, 17 Feb. 2020, [Peer-reviewed]
  English, Scientific journal
• Disturbance of the Front Region of Magnetic Reconnection Outflow Jets due to the Lower-Hybrid Drift Instability
  T. K. M. Nakamura; T. Umeda; R. Nakamura; H. S. Fu; M. Oka
  Physical Review Letters, 123, 23, American Physical Society (APS), 02 Dec. 2019, [Peer-reviewed]
  English, Scientific journal
• Mach number and plasma beta dependence of the ion temperature perpendicular to the external magnetic field in the transition region of perpendicular collisionless shocks
  Ryo Yamazaki; Ayato Shinoda; Takayuki Umeda; Shuichi Matsukiyo
  AIP Advances, 9, 12, AIP Publishing, 01 Dec. 2019, [Peer-reviewed]
  English, Scientific journal
• Vlasov code simulation of contact discontinuities
  Takayuki Umeda; Naru Tsujine; Yasuhiro Nariyuki
  Physics of Plasmas, 26, 10, AIP Publishing, 01 Oct. 2019, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Introduction to Basic Space Plasma Physics and Its Methods for Computer Simulation
  Takayuki UMEDA
  JAPANESE JOURNAL OF MULTIPHASE FLOW, 33, 3, 249, 257, The Japanese Society for Multiphase Flow, 15 Sep. 2019, [Invited], [Lead author]
  Japanese, Scientific journal
• Multi-step Boris rotation schemes for Lorentz force equation of charged particles
  Takayuki Umeda
  Computer Physics Communications, 237, 37, 41, Elsevier BV, Apr. 2019, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835065
• Full particle-in-cell simulation of the interaction between two plasmas for laboratory experiments on the generation of magnetized collisionless shocks with high-power lasers
  Takayuki Umeda; Ryo Yamazaki; Yutaka Ohira; Natsuki Ishizaka; Shin Kakuchi; Yasuhiro Kuramitsu; Shuichi Matsukiyo; Itaru Miyata; Taichi Morita; Youichi Sakawa; Takayoshi Sano; Shuto Sei; Shuta J. Tanaka; Hirohumi Toda; Sara Tomita
  Physics of Plasmas, 26, 3, 01 Mar. 2019, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835065
• Magnetosonic/whistler mode turbulence influences on ion dynamics
  S. Saito; Y. Nariyuki; T. Umeda
  Physics of Plasmas, 25, 12, AIP Publishing, 01 Dec. 2018, [Peer-reviewed]
  English, Scientific journal, 45398882
• On the Boris solver in particle-in-cell simulation
  Seiji Zenitani; Takayuki Umeda
  Physics of Plasmas, 25, 11, AIP Publishing, 01 Nov. 2018, [Peer-reviewed]
  English, Scientific journal
• Performance Comparison of Eulerian Kinetic Vlasov Code Between Xeon Phi KNL and Xeon Broadwell
  Takayuki Umeda; Keiichiro Fukazawa
  Methods and Applications for Modeling and Simulation of Complex Systems, AsiaSim 2018, Communications in Computer and Information Science, 946, 143, 150, Springer Singapore, 18 Oct. 2018, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• Oblique Ion‐Scale Magnetotail Flux Ropes Generated by Secondary Tearing Modes
  Wai‐Leong Teh; Takuma Nakamura; Rumi Nakamura; Takayuki Umeda
  Journal of Geophysical Research: Space Physics, 123, 10, 8122, 8130, American Geophysical Union (AGU), 08 Oct. 2018, [Peer-reviewed]
  English, Scientific journal, Abstract
  
  We examine Magnetospheric Multiscale observations of three ion‐scale magnetic flux ropes (diameter ~6–9 ion inertial lengths) in the Earth's magnetotail reconnection diffusion region with a small guide field. During the event, the electron reconnection exhaust reversed direction together with the reversal of normal magnetic field component. After that, the three ion‐scale flux ropes were observed near the ion diffusion region, in which flat‐top distributions were found at the field‐aligned electrons (<2 keV). The axis orientation and motion velocity of the flux ropes are determined by minimum variance analysis of the electric field component along the flux rope axis, using single‐spacecraft measurements. Results show that the three flux rope axes form 13°, 55°, and 55° to the guide field direction and are mostly tilted toward the direction of the reconnecting field. These results are also validated by multiple‐spacecraft analysis methods. It is found that the tilted angles agree reasonably well with the predicted angles for secondary tearing modes, suggesting that these ion‐scale flux ropes are likely generated by secondary tearing instabilities as those recently found in the three‐dimensional kinetic simulations of turbulent magnetic reconnection.
• Electromagnetic linear dispersion relation for plasma with a drift across magnetic field revisited
  Takayuki Umeda; Takuma K. M. Nakamura
  Physics of Plasmas, 25, 10, AIP Publishing, 01 Oct. 2018, [Peer-reviewed], [Lead author]
  English, Scientific journal, A current across the magnetic field is formed in various situations in plasma. The relative drift between ions and electrons due to the cross-field current becomes a source of various microscopic instabilities. A fully electromagnetic and kinetic linear dispersion relation for plasma with a drift across magnetic field is derived by assuming a uniform background plasma. The dielectric permittivity tensor for shifted Maxwellian velocity distributions is also presented. Linear dispersion relations obtained by using the new dielectric permittivity tensor were confirmed by comparison with the previous studies and with particle-in-cell simulation results., 13835064;13835065
• Periodic self-reformation of rippled perpendicular collisionless shocks in two dimensions
  Takayuki Umeda; Yuki Daicho
  Annales Geophysicae, 36, 4, 1047, 1055, Copernicus GmbH, 01 Aug. 2018, [Peer-reviewed], [Lead author]
  English, Scientific journal, Abstract. Large-scale two-dimensional (2-D) full particle-in-cell (PIC) simulations arecarried out for studying periodic self-reformation of a supercriticalcollisionless perpendicular shock with an Alfvén–Mach number MA∼6. Previous self-consistent one-dimensional (1-D) hybrid and full PICsimulations have demonstrated that the periodic reflection of upstream ionsat the shock front is responsible for the formation and vanishing of theshock-foot region on a timescale of the local ion cyclotron period, which wasdefined as the reformation of (quasi-)perpendicular shocks. The present 2-D full PIC simulations with different ion-to-electron massratios show that the dynamics at the shock front is strongly modified bylarge-amplitude ion-scale fluctuations at the shock overshoot, which areknown as ripples. In the run with a small mass ratio, the simultaneous enhancement of the shockmagnetic field and the reflected ions take place quasi-periodically, which isidentified as the reformation. In the runs with large mass ratios, thesimultaneous enhancement of the shock magnetic field and the reflected ionsoccur randomly in time, and the shock magnetic field is enhanced on atimescale much shorter than the ion cyclotron period. These results indicate a coupling between the shock-front ripples andelectromagnetic microinstabilities in the foot region in the runs with largemass ratios. Keywords. Space plasma physics (wave–particle interactions)
• Decay of nonlinear whistler mode waves: 1D versus 2D
  Takayuki Umeda; Shinji Saito; Yasuhiro Nariyuki
  Physics of Plasmas, 25, 7, AIP Publishing, 01 Jul. 2018, [Peer-reviewed], [Lead author]
  English, Scientific journal, Direct comparison between one-dimensional (1D) and two-dimensional (2D) models for the development of a nonlinear, short-wavelength, and monochromatic electromagnetic whistler mode wave is made by means of fully electromagnetic particle-in-cell simulations. The 1D and 2D simulations are performed for low beta conditions in which the plasma pressure is much lower than the magnetic pressure, although the plasma kinetic energy in the direction perpendicular to the ambient magnetic field is highly dominant due to the velocity field of the imposed parent whistler mode wave. A three-wave parametric decay of the parent whistler mode wave was reconfirmed in the 1D simulation. On the other hand, a rapid decay of the parent whistler mode wave thorough a five-wave interaction or double three-wave interactions was seen in the 2D simulation. Electron heating processes in the 2D simulation are also different from those in the 1D simulation. It is suggested that the present 2D decay process is a new instability which is quite different from velocity space instabilities driven by temperature/energy anisotropy., 13835065
• A three-step Boris integrator for Lorentz force equation of charged particles
  Takayuki Umeda
  Computer Physics Communications, 228, 1, 4, Elsevier BV, Jul. 2018, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835065
• Performance Analysis of CPU and DRAM Power Constrained Systems with Magnetohydrodynamic Simulation Code
  Keiichiro Fukazawa; Masatsugu Ueda; Yuichi Inadomi; Mutsumi Aoyagi; Takayuki Umeda; Koji Inoue
  2018 IEEE 20th International Conference on High Performance Computing and Communications; IEEE 16th International Conference on Smart City; IEEE 4th International Conference on Data Science and Systems (HPCC/SmartCity/DSS), 626, 631, IEEE, Jun. 2018, [Peer-reviewed]
  English, International conference proceedings
• 宇宙プラズマの運動論シミュレーション
  梅田 隆行
  計算数理工学レビュー, 2018, 1, 27, 35, 日本計算数理工学会, Mar. 2018, [Invited], [Lead author], [Domestic magazines]
  Japanese, Scientific journal
• Performance Evaluation and Optimization of MagnetoHydroDynamic Simulation for Planetary Magnetosphere with Xeon Phi KNL
  Keiichiro Fukazawa; Takeshi Soga; Takayuki Umeda; Takeshi Nanri
  Parallel Computing is Everywhere, Advances in Parallel Computing, 32, 178, 187, IOS Press BV, 2018, [Peer-reviewed]
  English, International conference proceedings
• Non-MHD effects in the nonlinear development of the MHD-scale Rayleigh-Taylor instability
  Takayuki Umeda; Yasutaka Wada
  Physics of Plasmas, 24, 7, 01 Jul. 2017, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835064
• Generation of intermittent ion acoustic waves in whistler-mode turbulence
  S. Saito; Y. Nariyuki; T. Umeda
  Physics of Plasmas, 24, 7, 29 Jun. 2017, [Peer-reviewed]
  English, Scientific journal, 45398882
• Rapid decay of nonlinear whistler waves in two dimensions: Full particle simulation
  Takayuki Umeda; Shinji Saito; Yasuhiro Nariyuki
  Physics of Plasmas, 24, 5, 26 Apr. 2017, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835064;13835065
• Secondary instabilities in the collisionless Rayleigh-Taylor instability: Full kinetic simulation
  Takayuki Umeda; Yasutaka Wada
  Physics of Plasmas, 23, 11, 01 Nov. 2016, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835064;13835065
• Performance comparison of Eulerian kinetic Vlasov code between flat-MPI parallelism and hybrid parallelism on Fujitsu FX100 supercomputer
  Takayuki Umeda; Keiichiro Fukazawa
  Proceedings of the 23rd European MPI Users' Group Meeting, 218, 221, 25 Sep. 2016, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• Three‐dimensional development of front region of plasma jets generated by magnetic reconnection
  T. K. M. Nakamura; R. Nakamura; W. Baumjohann; T. Umeda; I. Shinohara
  Geophysical Research Letters, 43, 16, 8356, 8364, 26 Aug. 2016, [Peer-reviewed]
  English, Scientific journal
• Evaluating gyro-viscosity in the Kelvin-Helmholtz instability by kinetic simulations
  Takayuki Umeda; Natsuki Yamauchi; Yasutaka Wada; Satoshi Ueno
  Physics of Plasmas, 23, 5, 01 May 2016, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835064
• Toward the Generation of Magnetized Collisionless Shocks with High-Power Lasers
  Yoshitaka SHOJI; Ryo YAMAZAKI; Sara TOMITA; Yushiro KAWAMURA; Yutaka OHIRA; Satoshi TOMIYA; Yoichi SAKAWA; Takayoshi SANO; Yukiko HARA; Sarana KONDO; Hiroshi SHIMOGAWARA; Shuichi MATSUKIYO; Taichi MORITA; Kentaro TOMITA; Hitoki YONEDA; Kazunori NAGAMINE; Yasuhiro KURAMITSU; Toseo MORITAKA; Naofumi OHNISHI; Takayuki UMEDA; Hideaki TAKABE
  Plasma and Fusion Research, 11, 3401031, 3401031, Japan Society of Plasma Science and Nuclear Fusion Research, 2016, [Peer-reviewed]
  English, International conference proceedings
• Hybrid parallelization of hyper-dimensional Vlasov code with OpenMP loop collapse directive
  Takayuki Umeda; Keiichiro Fukazawa
  Parallel Computing: On the Road to Exascale, Advances in Parallel Computing, 27, 265, 274, Elsevier B.V., 2016, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• Performance Comparison of Open-Source Parallel Sorting with OpenMP
  Takayuki Umeda; Shuhei Oya
  2015 Third International Symposium on Computing and Networking (CANDAR), 334, 340, Dec. 2015, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• Note on one-fluid modeling of low-frequency Alfvénic fluctuations in a solar wind plasma with multi-ion components
  Y. Nariyuki; T. Umeda; T. K. Suzuki; T. Hada
  Physics of Plasmas, 22, 12, 01 Dec. 2015, [Peer-reviewed]
  English, Scientific journal
• Nonlinear damping of a finite amplitude whistler wave due to modified two stream instability
  Shinji Saito; Yasuhiro Nariyuki; Takayuki Umeda
  Physics of Plasmas, 22, 7, 01 Jul. 2015, [Peer-reviewed]
  Scientific journal
• A high-resolution global Vlasov simulation of a small dielectric body with a weak intrinsic magnetic field on the K computer
  Takayuki Umeda; Keiichiro Fukazawa
  Earth, Planets and Space, 67, 1, 11 Apr. 2015, [Peer-reviewed], [Invited], [Lead author]
  English, Scientific journal
• ELECTRON ACCELERATION DURING THE DECAY OF NONLINEAR WHISTLER WAVES IN LOW-BETA ELECTRON-ION PLASMA
  Takayuki Umeda; Shinji Saito; Yasuhiro Nariyuki
  The Astrophysical Journal, 794, 1, 63, 63, 24 Sep. 2014, [Peer-reviewed], [Lead author]
  English, Scientific journal, 45398882;13835065
• Ion kinetic effects on nonlinear processes of the Kelvin–Helmholtz instability
  Takayuki Umeda; Satoshi Ueno; Takuma K M Nakamura
  Plasma Physics and Controlled Fusion, 56, 7, 075006, 075006, 08 May 2014, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835066;13835067
• Entry of solar-wind ions into the wake of a small body with a magnetic anomaly: A global Vlasov simulation
  Takayuki Umeda; Yosuke Ito
  Planetary and Space Science, 93-94, 35, 40, Apr. 2014, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835066;13835067
• Some remarks on the diffusion regions in magnetic reconnection
  Seiji Zenitani; Takayuki Umeda
  Physics of Plasmas, 21, 3, 01 Mar. 2014, [Peer-reviewed]
  English, Scientific journal
• Ion acceleration by parallel propagating nonlinear Alfvén wave packets in a radially expanding plasma
  Y. Nariyuki; T. Umeda; T. K. Suzuki; T. Hada
  Nonlinear Processes in Geophysics, 21, 1, 339, 346, 27 Feb. 2014, [Peer-reviewed]
  English, Scientific journal
• Dynamics and microinstabilities at perpendicular collisionless shock: A comparison of large-scale two-dimensional full particle simulations with different ion to electron mass ratio
  Takayuki Umeda; Yoshitaka Kidani; Shuichi Matsukiyo; Ryo Yamazaki
  Physics of Plasmas, 21, 2, 022102, 022102, Feb. 2014, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835065
• Performance Tuning of Vlasov Code for Space Plasma on the K Computer
  Takayuki Umeda; Keiichiro Fukazawa
  AsiaSim 2014, Communications in Computer and Information Science, 474, 127, 138, Springer Berlin Heidelberg, 2014, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• Performance measurements of MHD simulation for planetary magnetosphere on peta-scale computer FX10
  Keiichiro Fukazawa; Takeshi Nanri; Takayuki Umeda
  Parallel Computing: Accelerating Computational Science and Engineering (CSE),Advances in Parallel Computing, 25, 387, 394, IOS Press BV, 2014, [Peer-reviewed]
  English, International conference proceedings
• Global Vlasov simulation on magnetospheres of astronomical objects
  Takayuki Umeda; Yosuke Ito; Keiichiro Fukazawa
  Journal of Physics: Conference Series, 454, 012005, 012005, IOP Publishing, 12 Aug. 2013, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• A primitive kinetic-fluid model for quasi-parallel propagating magnetohydrodynamic waves
  Y. Nariyuki; S. Saito; T. Umeda
  Physics of Plasmas, 20, 7, 01 Jul. 2013, [Peer-reviewed]
  English, Scientific journal
• Performance Measurement of Parallel Vlasov Code for Space Plasma on Scalar-Type Supercomputer Systems with Large Number of Cores
  Takayuki Umeda; Keiichiro Fukazawa
  AsiaSim 2013, Communications in Computer and Information Science, 402, 561, 569, Springer Berlin Heidelberg, 2013, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• Performance Evaluation of Magnetohydrodynamics Simulation for Magnetosphere on K Computer
  Keiichiro Fukazawa; Takeshi Nanri; Takayuki Umeda
  AsiaSim2013, Communications in Computer and Information Science, 402, 570, 576, Springer Berlin Heidelberg, 2013, [Peer-reviewed]
  English, In book
• A numerical electromagnetic linear dispersion relation for Maxwellian ring-beam velocity distributions
  Takayuki Umeda; Shuichi Matsukiyo; Takanobu Amano; Yoshizumi Miyoshi
  Physics of Plasmas, 19, 7, 01 Jul. 2012, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Vlasov simulation of electrostatic solitary structures in multi‐component plasmas
  Takayuki Umeda; Maha Ashour‐Abdalla; Jolene S. Pickett; Melvyn L. Goldstein
  Journal of Geophysical Research: Space Physics, 117, A5, 16 May 2012, [Peer-reviewed], [Lead author]
  English, Scientific journal
• A non-oscillatory and conservative semi-Lagrangian scheme with fourth-degree polynomial interpolation for solving the Vlasov equation
  Takayuki Umeda; Yasuhiro Nariyuki; Daichi Kariya
  Computer Physics Communications, 183, 5, 1094, 1100, May 2012, [Peer-reviewed]
  English, Scientific journal
• A Scalable Full-Electromagnetic Vlasov Solver for Cross-Scale Coupling in Space Plasma
  Takayuki Umeda; Keiichiro Fukazawa; Yasuhiro Nariyuki; Tatsuki Ogino
  IEEE Transactions on Plasma Science, 40, 5, 1421, 1428, May 2012, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Microinstabilities at perpendicular collisionless shocks: A comparison of full particle simulations with different ion to electron mass ratio
  Takayuki Umeda; Yoshitaka Kidani; Shuichi Matsukiyo; Ryo Yamazaki
  Physics of Plasmas, 19, 4, 01 Apr. 2012, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Modified two‐stream instability at perpendicular collisionless shocks: Full particle simulations
  Takayuki Umeda; Yoshitaka Kidani; Shuichi Matsukiyo; Ryo Yamazaki
  Journal of Geophysical Research: Space Physics, 117, A3, 06 Mar. 2012, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Performance measurement of magnetohydrodynamic code for space plasma on typical scalar-type supercomputer systems with a large number of cores
  Keiichiro Fukazawa; Takayuki Umeda
  The International Journal of High Performance Computing Applications, 26, 3, 310, 318, 09 Feb. 2012, [Peer-reviewed]
  English, Scientific journal
• Effect of ion cyclotron motion on the structure of wakes: A Vlasov simulation
  Takayuki Umeda
  Earth, Planets and Space, 64, 2, 231, 236, Feb. 2012, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Performance Measurement of Parallel Vlasov Code for Space Plasma on Various Scalar-Type Supercomputer Systems
  Takayuki Umeda; Keiichiro Fukazawa
  Algorithms and Architectures for Parallel Processing, ICA3PP 2012, Lecture Notes in Computer Science, 7439, 233, 240, Springer Berlin Heidelberg, 2012, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• RELATIVISTIC ELECTRON SHOCK DRIFT ACCELERATION IN LOW MACH NUMBER GALAXY CLUSTER SHOCKS
  S. Matsukiyo; Y. Ohira; R. Yamazaki; T. Umeda
  The Astrophysical Journal, 742, 1, 47, 47, 03 Nov. 2011, [Peer-reviewed]
  English, Scientific journal
• SUPPRESSION OF REFLECTED ELECTRONS BY KINETIC ALFVÉN TURBULENCE IN A QUASI-PERPENDICULAR SHOCK: PARTICLE-IN-CELL SIMULATIONS
  S. Saito; T. Umeda
  The Astrophysical Journal, 736, 1, 35, 35, 01 Jul. 2011, [Peer-reviewed]
  English, Scientific journal, 13835065
• A new numerical method for simulating the solar wind Alfvén waves: Development of the Vlasov–MHD model
  Y. Nariyuki; T. Umeda; T. Kumashiro; T. Hada
  Planetary and Space Science, 59, 8, 767, 771, Jun. 2011, [Peer-reviewed]
  English, Scientific journal
• Cross-scale coupling at a perpendicular collisionless shock
  Takayuki Umeda; Masahiro Yamao; Ryo Yamazaki
  Planetary and Space Science, 59, 7, 449, 455, May 2011, [Peer-reviewed]
  English, Scientific journal
• Quasilinear theory and simulation of Buneman instability
  J. Pavan; P. H. Yoon; T. Umeda
  Physics of Plasmas, 18, 4, 01 Apr. 2011, [Peer-reviewed]
  English, Scientific journal
• Self-consistent kinetic numerical simulation model for ring current particles in the Earth's inner magnetosphere
  Takanobu Amano; Kanako Seki; Yoshizumi Miyoshi; Takayuki Umeda; Yosuke Matsumoto; Yusuke Ebihara; Shinji Saito
  Journal of Geophysical Research: Space Physics, 116, A2, n/a, n/a, 24 Feb. 2011, [Peer-reviewed]
  English, Scientific journal
• Modeling nonlinear development of Buneman instability with linear dispersion theory
  Neeraj Jain; Takayuki Umeda; Peter H Yoon
  Plasma Physics and Controlled Fusion, 53, 2, 025010, 025010, 07 Jan. 2011, [Peer-reviewed]
  English, Scientific journal
• Vlasov Code Simulation of Cross-scale Coupling in Space Plasmas
  T. Umeda; Y. Matsumoto; T. K. M. Nakamura; K. Fukazawa; T. Ogino
  5th International Conference of Numerical Modeling of Space Plasma Flows (ASTRONUM 2010), 444, 182, +, 2011, [Peer-reviewed], [Lead author]
  English, International conference proceedings
• Vlasov simulation of the interaction between the solar wind and a dielectric body
  Takayuki Umeda; Tetsuya Kimura; Kentaro Togano; Keiichiro Fukazawa; Yosuke Matsumoto; Takahiro Miyoshi; Naoki Terada; Takuma K. M. Nakamura; Tatsuki Ogino
  Physics of Plasmas, 18, 1, 012908, 012908, Jan. 2011, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Nonlinear turbulence theory and simulation of Buneman instability
  P. H. Yoon; T. Umeda
  Physics of Plasmas, 17, 11, 112317, 112317, Nov. 2010, [Peer-reviewed]
  English, Scientific journal
• On the reformation at quasi‐ and exactly perpendicular shocks: Full particle‐in‐cell simulations
  Takayuki Umeda; Yoshitaka Kidani; Masahiro Yamao; Shuichi Matsukiyo; Ryo Yamazaki
  Journal of Geophysical Research: Space Physics, 115, A10, 29 Oct. 2010, [Peer-reviewed], [Lead author]
  English, Scientific journal
• The HLLD Approximate Riemann Solver for Magnetospheric Simulation
  Takahiro Miyoshi; Naoki Terada; Yosuke Matsumoto; Keiichiro Fukazawa; Takayuki Umeda; Kanya Kusano
  IEEE Transactions on Plasma Science, 38, 9, 2236, 2242, Sep. 2010, [Peer-reviewed]
  English, Scientific journal
• Performance Measurement of Magnetohydrodynamic Code for Space Plasma on the Various Scalar-Type Supercomputer Systems
  Keiichiro Fukazawa; Takayuki Umeda; Takahiro Miyoshi; Naoki Terada; Yosuke Matsumoto; Tatsuki Ogino
  IEEE Transactions on Plasma Science, 38, 9, 2254, 2259, Sep. 2010, [Peer-reviewed]
  English, Scientific journal
• Comparative Study of Global MHD Simulations of the Terrestrial Magnetosphere With Different Numerical Schemes
  Yosuke Matsumoto; Naoki Terada; Takahiro Miyoshi; Keiichiro Fukazawa; Takayuki Umeda; Tatsuki Ogino; Kanako Seki
  IEEE Transactions on Plasma Science, 38, 9, 2229, 2235, Sep. 2010, [Peer-reviewed]
  English, Scientific journal
• Structures of diffusion regions in collisionless magnetic reconnection
  Takayuki Umeda; Kentaro Togano; Tatsuki Ogino
  Physics of Plasmas, 17, 5, 01 May 2010, [Peer-reviewed]
  English, Scientific journal
• On the nonlinearity of the Langmuir turbulence excited by a weak electron beam-plasma interaction
  Y. Nariyuki; T. Umeda
  Physics of Plasmas, 17, 5, 01 May 2010, [Peer-reviewed]
  English, Scientific journal
• Full electromagnetic Vlasov code simulation of the Kelvin–Helmholtz instability
  Takayuki Umeda; Jun-ichiro Miwa; Yosuke Matsumoto; Takuma K. M. Nakamura; Kentaro Togano; Keiichiro Fukazawa; Iku Shinohara
  Physics of Plasmas, 17, 5, 01 May 2010, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Electromagnetic plasma emission during beam‐plasma interaction: Parametric decay versus induced scattering
  Takayuki Umeda
  Journal of Geophysical Research: Space Physics, 115, A1, 14 Jan. 2010, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Vlasov simulation of finite amplitude magnetohydrodynamic waves in the solar wind: Development of Vlasov-Hall-MHD code
  T. Kumashiro; T. Hada; Y. Nariyuki; T. Umeda
  Journal of Plasma and Fusion Research SERIES, 8, 831, 836, The Japan Society of Plasma Science and Nuclear Fusion Research, Sep. 2009, [Peer-reviewed], [Domestic magazines]
  English, Scientific journal
• Implementation of a non-oscillatory and conservative scheme into magnetohydrodynamic equations
  Shin Tanaka; Takayuki Umeda; Yosuke Matsumoto; Takahiro Miyoshi; Tatsuki Ogino
  Earth, Planets and Space, 61, 7, 895, 903, Jul. 2009, [Peer-reviewed]
  English, Scientific journal
• Cluster observations and numerical modeling of energy‐dispersed ionospheric H⁺ ions bouncing at the plasma sheet boundary layer
  J. M. Bosqued; M. Ashour‐Abdalla; T. Umeda; M. El Alaoui; V. Peroomian; H. U. Frey; A. Marchaudon; H. Laakso
  Journal of Geophysical Research: Space Physics, 114, A4, 28 Apr. 2009, [Peer-reviewed]
  English, Scientific journal
• ELECTRON ACCELERATION AT A LOW MACH NUMBER PERPENDICULAR COLLISIONLESS SHOCK
  Takayuki Umeda; Masahiro Yamao; Ryo Yamazaki
  ASTROPHYSICAL JOURNAL, 695, 1, 574, 579, Apr. 2009, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Two-dimensional full-electromagnetic Vlasov code with conservative scheme and its application to magnetic reconnection
  Takayuki Umeda; Kentaro Togano; Tatsuki Ogino
  Computer Physics Communications, 180, 3, 365, 374, Mar. 2009, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Vlasov simulation of Langmuir decay instability
  Takayuki Umeda; Tetsuya Ito
  Physics of Plasmas, 15, 8, 01 Aug. 2008, [Peer-reviewed], [Lead author]
  English, Scientific journal
• A conservative and non-oscillatory scheme for Vlasov code simulations
  Takayuki Umeda
  Earth, Planets and Space, 60, 7, 773, 779, Springer Science and Business Media LLC, Jul. 2008, [Peer-reviewed], [Lead author]
  English, Scientific journal, Abstract
  
  A new numerical positive interpolation technique for conservation laws and its application to Vlasov code simulations are presented. In recent Vlasov simulation codes, the Vlasov equation is solved based on the numerical interpolation method because of its simplicity of algorithm and its ease of programming. However, a large number of grid points are needed in both configuration and velocity spaces to suppress numerical diffusion. In this paper we propose a new high-order interpolation scheme for Vlasov simulations. The current scheme is non-oscillatory and conservative and is well-designed for Vlasov simulations. This is compared with the latest interpolation schemes by performing one-dimensional electrostatic Vlasov simulations.
• Two-dimensional Full Particle Simulation of a Perpendicular Collisionless Shock with a Shock-Rest-Frame Model
  Takayuki Umeda; Masahiro Yamao; Ryo Yamazaki
  The Astrophysical Journal, 681, 2, L85, L88, 17 Jun. 2008, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Generation of low-frequency electrostatic and electromagnetic waves as nonlinear consequences of beam–plasma interactions
  Takayuki Umeda
  Physics of Plasmas, 15, 6, 01 Jun. 2008, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Modeling PSBL high speed ion beams observed by Cluster and Double Star
  Maha Ashour-Abdalla; Jean-Michel Bosqued; Mostafa El-Alaoui; Vahé Peroomian; Takayuki Umeda; Raymond J. Walker
  Advances in Space Research, 41, 10, 1598, 1610, Jan. 2008, [Peer-reviewed]
  English, Scientific journal
• Numerical study of electrostatic electron cyclotron harmonic waves due to Maxwellian ring velocity distributions
  Takayuki Umeda
  Earth, Planets and Space, 59, 11, 1205, 1210, 30 Nov. 2007, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Parametric decay of circularly polarized Alfvén waves in the radially expanding solar wind
  Shin Tanaka; Tatsuki Ogino; Takayuki Umeda
  Journal of Geophysical Research: Space Physics, 112, A10, 30 Oct. 2007, [Peer-reviewed]
  English, Scientific journal
• Vlasov simulation of Langmuir wave packets
  T. Umeda
  Nonlinear Processes in Geophysics, 14, 5, 671, 679, 25 Oct. 2007, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Turbulent acceleration of superthermal electrons
  C.-M. Ryu; T. Rhee; T. Umeda; P. H. Yoon; Y. Omura
  Physics of Plasmas, 14, 10, 01 Oct. 2007, [Peer-reviewed]
  English, Scientific journal
• Particle‐in‐cell simulation of Maxwellian ring velocity distribution
  Takayuki Umeda; Maha Ashour‐Abdalla; David Schriver; Robert L. Richard; Ferdinand V. Coroniti
  Journal of Geophysical Research: Space Physics, 112, A4, 28 Apr. 2007, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Comparison of numerical interpolation schemes for one-dimensional electrostatic Vlasov code
  Takayuki Umeda; Maha Ashour-Abdalla; David Schriver
  Journal of Plasma Physics, 72, 06, 1057, 1057, 20 Dec. 2006, [Lead author]
  English, Scientific journal
• Full particle simulation of a perpendicular collisionless shock: A shock-rest-frame model
  Takayuki Umeda; Ryo Yamazaki
  Earth, Planets and Space, 58, 10, e41, e44, 13 Oct. 2006, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Nonlinear evolution of the electron two‐stream instability: Two‐dimensional particle simulations
  Takayuki Umeda; Yoshiharu Omura; Taketoshi Miyake; Hiroshi Matsumoto; Maha Ashour‐Abdalla
  Journal of Geophysical Research: Space Physics, 111, A10, 07 Oct. 2006, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Vlasov simulation of amplitude-modulated Langmuir waves
  Takayuki Umeda
  Physics of Plasmas, 13, 9, 01 Sep. 2006, [Peer-reviewed], [Lead author]
  English, Scientific journal, 13835070
• Cluster observations of energetic ionospheric ion beams in the auroral region: Acceleration and associated energy‐dispersed precipitation
  J. M. Bosqued; M. Ashour‐Abdalla; A. Marchaudon; H. Laakso; T. Umeda; M. El Alaoui; V. Peroomian; H. Rème; G. Paschmann; M. Dunlop; A. Fazakerley
  Geophysical Research Letters, 33, 12, 17 Jun. 2006, [Peer-reviewed]
  English, Scientific journal
• Study on Nonlinear Processes of Electron Beam Instabilities via Computer Simulations
  Takayuki Umeda
  Ph.D. Thesis, Graduate School of Informatics, Kyoto University, Mar. 2004, [Peer-reviewed], [Lead author]
  English, Doctoral thesis

  
  Preprint
• Two‐dimensional particle simulation of electromagnetic field signature associated with electrostatic solitary waves
  Takayuki Umeda; Yoshiharu Omura; Hiroshi Matsumoto
  Journal of Geophysical Research: Space Physics, 109, A2, American Geophysical Union (AGU), 13 Feb. 2004, [Peer-reviewed], [Lead author]
  English, Scientific journal
• A new charge conservation method in electromagnetic particle-in-cell simulations
  T Umeda; Y Omura; T Tominaga; H Matsumoto
  Computer Physics Communications, 156, 1, 73, 85, Dec. 2003, [Peer-reviewed], [Lead author]
  English, Scientific journal
• Two-Dimensional Particle Simulation of Electrostatic Solitary Waves with an Open Boundary Condition
  T. Umeda; Y. Omura; H. Matsumoto; H. Usui
  PLASMA PHYSICS: 11th International Congress on Plasma Physics: ICPP2002, AIP Conference Proceedings, 669, 735, 738, 11 Jun. 2003, [Lead author]
  English, International conference proceedings
• Particle simulation of plasma response to an applied electric field parallel to magnetic field lines
  Y. Omura; W. J. Heikkila; T. Umeda; K. Ninomiya; H. Matsumoto
  Journal of Geophysical Research: Space Physics, 108, A5, 17 May 2003, [Peer-reviewed]
  English, Scientific journal
• Harmonic Langmuir waves. I. Nonlinear dispersion relation
  P. H. Yoon; R. Gaelzer; T. Umeda; Y. Omura; H. Matsumoto
  Physics of Plasmas, 10, 2, 364, 372, 01 Feb. 2003, [Peer-reviewed]
  English, Scientific journal
• Harmonic Langmuir waves. II. Turbulence spectrum
  R. Gaelzer; P. H. Yoon; T. Umeda; Y. Omura; H. Matsumoto
  Physics of Plasmas, 10, 2, 373, 381, 01 Feb. 2003, [Peer-reviewed]
  English, Scientific journal
• Harmonic Langmuir waves. III. Vlasov simulation
  T. Umeda; Y. Omura; P. H. Yoon; R. Gaelzer; H. Matsumoto
  Physics of Plasmas, 10, 2, 382, 391, 01 Feb. 2003, [Peer-reviewed], [Lead author]
  English, Scientific journal, 44606004
• Formation of electrostatic solitary waves in space plasmas: Particle simulations with open boundary conditions
  T. Umeda; Y. Omura; H. Matsumoto; H. Usui
  Journal of Geophysical Research: Space Physics, 107, A12, American Geophysical Union (AGU), 18 Dec. 2002, [Peer-reviewed], [Lead author]
  English, Scientific journal, 44606004
• An improved masking method for absorbing boundaries in electromagnetic particle simulations
  Takayuki Umeda; Yoshiharu Omura; Hiroshi Matsumoto
  Computer Physics Communications, 137, 2, 286, 299, Jun. 2001, [Peer-reviewed], [Lead author]
  English, Scientific journal, 44606004
• Observational evidence of dissipative small scale processes: Geotail spacecraft observation and simulation of electrostatic solitary waves
  Y Omura; H Kojima; T Umeda; H Matsumoto
  Astrophysics and Space Science, 277, 1-2, 45, 57, 2001, [Peer-reviewed]
  English, Scientific journal

• プラズマの計算科学 : 宇宙・核融合のマクロとミクロ描像を解き明かすMHDとPICシミュレーション
  梅田 隆行(編); 金田 行雄; 笹井 理生(監修)
  共立出版, Nov. 2024, 9784320122734, xi, 315p, 図版 [2] p (ページ付なし), Japanese
• Computer Physics
  Takayuki Umeda, Simulation of collisionless plasma with the Vlasov method
  Nova Science, Dec. 2012, 9781613247907, 315-332, English, Scholarly book, Numerical schemes for solving the Vlasov-Maxwell system of equations are presented. Our Universe is filled with collisionless plasma, which is a dielectric medium with nonlinear interactions between charged particles and electromagnetic fields. Thus computer simulations play an essential role in studies of such highly nonlinear systems. The full kinetics of collisionless plasma is described by the Vlasov-Maxwell equations. Since the Vlasov equation treats charged particles as position-velocity phase-space distribution functions in hyper dimensions, huge supercomputers and highly-scalable parallel codes are essential. Recently, a new parallel Vlasov-Maxwell solver is developed by adopting a stable but less-dissipative scheme for time integration of conservation laws, which has successfully achieved a high scalability on massively parallel supercomputers with multi-core scalar processors. The new code has applied to 2P3V (two dimensions for position and three dimensions for velocity) problems of cross-scale plasma processes such as magnetic reconnection, Kelvin-Helmholtz instability and the interaction between the solar wind and an asteroid. © 2012 Nova Science Publishers, Inc. All rights reserved., [Contributor]
• Wave Propagation
  Takayuki Umeda, Electromagnetic waves in plasma
  In Tech, Mar. 2011, 9789533072753, 311-330, English, Scholarly book, [Contributor]
• Space Plasma Simulation, Lecture Notes in Physics, Volume 615
  Yoshiharu Omura; Takayuki Umeda; Hiroshi Matsumoto, Simulation of electron beam instabilities and nonlinear potential structures
  Springer Berlin Heidelberg, 20 Mar. 2003, 9783540006985, 79-92, English, Scholarly book, [Peer-reviewed], [Contributor]

• 情報理工学実験Ⅱ, 2024年, 学士課程, 工学部
• コンピュータシステム, 2024年, 学士課程, 工学部
• 情報理工学演習Ⅰ, 2024年, 学士課程, 工学部

• Jan. 2024 - Present
  Association of Asia Pacific Physical Societies, Division of Plasma Physics
• Feb. 2021 - Present
  IEEE
• 2009 - Present
  Japan Geoscience Union
• 2003 - Present
  Americal Geophysical Union
• 2000 - Present
  Society of Geomagnetism and Earth, Planetary and Space Sciences

• Fortran90 wrapper for HDF5
  Takayuki Umeda, 01 Mar. 2024 - Present, Fortran90 wrapper subroutines and sample codes for writing/reading HDF5 datasets, [Software]
• VLASOV1m
  Takayuki Umeda, 27 Jul. 2013 - Present, One-dimensional electrostatic Vlasov code in MATLAB, [Software]

• Study of a new electromagnetic fluid simulation code for "post-Fugaku" era
  Grants-in-Aid for Scientific Research
  01 Apr. 2024 - 31 Mar. 2029
  梅田 隆行
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 24K00603
• How do fluid simulations reproduce kinetic simulation results?
  Grants-in-Aid for Scientific Research
  Apr. 2019 - Mar. 2024
  梅田 隆行
  宇宙プラズマ環境変動の予測において計算機シミュレーションは今後不可欠な手段となる。既存の磁気流体力学(MHD)方程式に基づくプラズマ流体シミュレーションでは、慣性効果、圧力テンソルの非対角成分、熱輸送テンソルや四次以上の高次モーメント量などの非MHD項は無視されている。本研究では、第一原理運動論プラズマシミュレーションと流体ミュレーションとの直接比較によって、非MHD項である高次モーメント量が従来のMHD量に対してどのくらいの強度を持つのかを定量的に評価し、非MHD項の各項の重要性を議論する。また高次モーメント量を導入した新たな電磁流体方程式系を導出し、その数値シミュレーション手法を開発する。
  Thompson [1961]のジャイロ平均した速度分布関数の近似式に基づいて、三次及び四次モーメント量の近似式を導出した。また、ケルヴィン・ヘルムホルツ不安定性の2次元full-Vlasovシミュレーション結果より三次及び四次モーメント量を計算し、導出した近似式との直接比較を行った。その結果、四次モーメント量はよく近似できていることに対し、三次モーメント量はほどんど近似できていないことを示した。本研究グループの過去の研究において二次モーメント量もよく近似できていることを示した[Umeda et al. 2016]ため、この結果はThompson [1961]の奇数モーメント量の近似式を見直す必要があることを示唆する。
  1次元full-Vlasovシミュレーションによる接触不連続のパラメータサーベイを行い、Maxwell速度分布を持つプラズマ中ではMHD平衡解としての接触不連続が存在しないことを示唆した。更に、full-Vlasovシミュレーションと全く同一パラメータを用いた1次元hybrid-Vlasovシミュレーションとの直接比較を行い、接触不連続の崩壊の要因が三次モーメント量である熱輸送量であることを示した。この結果は、流体と運動論の差を作る要因の１つが三次モーメント量であることを示唆する。
  高次モーメント量を含む電磁流体方程式を導出し、差分化のための格子系の検討を行った。また、staggered格子系の方程式についての高次精度化スキームの検討を行い、1次元Maxwell方程式について従来のFDTD法を四次精度に拡張した。
  令和元年度の課題として設定した３つのうち、境界層の多次元full-Vlasovシミュレーションは順調に進んでいる。また磁場に沿った円柱座標系の回転方向に平均化したVlasov方程式を用いたThompson[1961]のモーメント近似法について、3次モーメント量である熱輸送テンソルの近似精度が悪いことを示した研究結果を出版した。4次モーメントまでを含んだ電磁流体方程式を導出し、計算手法の検討を行っている最中である。
  Vlasovシミュレーションについては計算を継続する。また磁場に沿った円柱座標系の回転方向に平均化したVlasov方程式を用いたThompson 1961のモーメント近似法について、平均化したVlasov方程式そのものについて、導出過程から見直す。四次モーメントまでを含んだ電磁流体方程式については、計算手法の検討を引き続き行い、また磁場に対するガウスの法則（磁場の無発散）を満たすため、staggered格子系の導入を試みる。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, Principal investigator, 19H01868
• Plasma heating/acceleration in kinetic plasma turbulence and its turbulence evolution
  Grants-in-Aid for Scientific Research
  01 Apr. 2014 - 31 Mar. 2019
  Saito Shinji; UMEDA takayuki
  We study kinetic plasma turbulence, where kinetic effect of charged particles are important in its dynamics, by using fully kinetic particle-in-cell simulations. We focus on heating/acceleration processes associated with dissipation of the kinetic turbulence.
  In this study we investigate nonlinear dynamics of whistler mode turbulence. In linear theory, whistler mode does not resonate with ions. However, the fully kinetic particle-in-cell simulations demonstrate that ions can be accelerated and/or heated by whistler mode turbulence through its nonlinear developments that include plasma instability and nonlinear intermittent nature of the kinetic turbulence.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, 26287119
• Study of unified numerical schemes for numerical simulations of electromagnetic fluid plasma: From MHD to multi fluids
  Grants-in-Aid for Scientific Research
  Apr. 2015 - Mar. 2018
  UMEDA TAKAYUKI
  The nonlinear evolution of the Kelvin-Helmholtz instability (KHI) and the Rayleigh-Taylor instability (RTI) at a density shear layer transverse to magnetic field in collisionless plasma is investigated by means of a fully kinetic Vlasov simulation with two spatial and two velocity dimensions. Several simulation runs with different ratio of the ion inertial length and/or ion gyro radius to the thickness of the initial shear layer have been performed to discuss “non-MHD effects” such as the ion inertial (Hall) effect and the ion finite Larmor radius (FLR) effect. The result shows that the instabilities develop symmetrically when neither Hall effect or FLR effect are available. An asymmetric development of the instabilities is seen when the Hall effect is available. When the FLR effect is available, a different type of instability with a spatial scale of ion gyro radius is generated, which disturbs the development of the primary instabilities.
  Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Nagoya University, Principal investigator, Competitive research funding, 15K13572
• Generation of cosmic-ray protons at collisionless shocks via hybrid particle-in-cell simulations
  Grants-in-Aid for Scientific Research
  Apr. 2014 - Mar. 2018
  UMEDA TAKAYUKI
  The computational speed of the particle-in-cell-type plasma simulation codes is accelerated by using the counting sort algorithm and the array-particle data structure. Large-scale two-dimensional particle-in-cell simulations are carried out by using the improved code for studying non-stationarity of perpendicular shocks called the reformation. The result implies that the existence of the reformation is controlled by types of micro-instabilities at the shock transition layer.
  One- and two-dimensional particle simulations are also carried out on the development of a large-amplitude whistler-mode waves in the shock transition layer. Relativistic electron acceleration is found in the 1D run. On the other hand, a rapid decay of whistler-mode waves through a new instability is found in the 2D run, which suppress the relativistic electron acceleration.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, Principal investigator, Competitive research funding, 26287041
• Basic plasma processes in the termination shock in a striped pulsar wind
  Grants-in-Aid for Scientific Research
  01 Apr. 2013 - 31 Mar. 2016
  Zenitani Seiji; SHINOHARA Iku; NAGAI Tsugunobu; UMEDA Takayuki; WADA Tomohide
  We conducted basic researches on magnetic reconnection and magnetohydrodynamic (MHD) shocks. We proposed a new definition of the central region of magnetic reconnection and then further discussed particle dynamics in the reconnection magnetic geometry. Next we organized a fundamental algorithm to deal with relativistically-moving plasma distribution in particle-in-cell (PIC) simulations. By using a relativistic PIC simulation, we studied the electromagnetic balance in the central region of relativistic magnetic reconnection. We also developed a shock-capturing MHD code, which is publicly available. We studied the interaction between magnetic reconnection and MHD shocks. We also proposed a new mechanism to explain gamma-ray flares in a Crab pulsar system, by using MHD simulations.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), National Astronomical Observatory of Japan, 25871054
• Six-dimensional plasma simulation
  Grants-in-Aid for Scientific Research
  Apr. 2013 - Mar. 2015
  UMEDA Takayuki
  A fully six-dimensional electromagnetic Vlasov code has been developed. Work arrays and memory space for the computation of the advection in the configuration space are substantially saved by the transposition of the data arrays for distribution functions. It is confirmed that the transposition efficiently accelerates the computational speed on x86 CPUs. While on SPARC CPUs, the computational efficiency becomes slightly worse.
  We also performed large-scale Vlasov simulation of the Kelvin-Helmholtz instability (KHI) and a weakly-magnetized small body. It is shown that ion-scale secondary instabilities taking place during the nonlinear development of MHD-scale primary KHI are affected by the structure of secondary velocity-shear layers of primary KH vortices. On the other hand, electron-scale charge separation does not affect the structure of MHD-scale magnetosphere but affects wave activities inside the magnetosphere.
  Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Nagoya University, Principal investigator, Competitive research funding, 25610144
• Study of cross-scale coupling in space plasma via large-scale Vlasov simulations
  Grants-in-Aid for Scientific Research
  2011 - 2012
  UMEDA Takayuki
  We study numerical schemes for the first-principle Vlasov code as a post-Peta-scale computer simulation technique of space plasma. We developed numerical algorithms for solving the collisionless Boltzmann (Vlasov) equation which is a hyper-dimensional conservation law. The new simulation code is parallelized for scalar massively parallel computers with more than 10,000 CPU cores. The new code is applied to various multi-scale processes in space plasma. The first global Vlasov simulation of a magnetized astronomical body is succeeded. Also, it is shown that temporal evolution of fluid-scale Kelvin-Helmholtz vortices generated at a velocity-shear layer is strongly affected by the particle-scale ion gyro motion.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Nagoya University, Principal investigator, Competitive research funding, 23740367
• Non-equilibrium plasmas associated with magnetohydrodynamic waves in solar wind plasmas
  Grants-in-Aid for Scientific Research
  2010 - 2012
  NARIYUKI Yasuhiro; UMEDA Takayuki; SAITO Shinji; SUZUKI Takeru; HADA Tohru; NARITA Yasuhito
  In the present study, the solar wind non-equilibrium plasmas associated with magnetohydrodynamic （MHD) waves are discussed. The main results are as follows: （1) The “apparent” temperature anisotropy associated with MHD waves corresponds to the magnetohydrodynamic equilibrium state （Alfven-Beltrami field), （2)Ion beams can be formed by the nonlinear steepening of the MHD waves propagating from the solar corona, （3)The low-frequency MHD waves are rapidly dissipated due to the presence of the beam-induced short-wavelength waves.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), 22740324
• Study of particle acceleration processes at collisionless shocks via next-generation and first-principle particle simulations
  Grants-in-Aid for Scientific Research
  2009 - 2011
  UMEDA Takayuki
  Large-scale two-dimensional full particle-in-cell simulations are carried out for studying non-stationarity of perpendicular shocks. It is confirmed that the persistence and absence of the self-reformation is controlled by micro-instabilities at the shock front. When electromagnetic whistler mode waves are strongly excited by the modified two-stream instability, both incoming and reflected ions are strongly scattered and the shock reformation becomes absent. On the other hand, when electrostatic waves are weakly excited or there is no micro-instabilities, reflected ions show a coherent behavior and the shock reformation is persistent. In this case, however, the reformation period is modified essentially due to the shock front ripples. The present simulation result suggests that the structure and dynamics of shocks are affected by the cross-scale coupling between electron-scale micro-instabilities and ion-scale shock-front ripples.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research on Innovative Areas (Research a proposed research project), Nagoya University, Principal investigator, Competitive research funding, 21200050
• Study of geospace storms based on a new observation-based model of the inner magnetosphere
  Grants-in-Aid for Scientific Research
  2008 - 2011
  SEKI Kanako; MIYOSHI Yoshizumi; AMANO Takanobu; SAITO Shinji; UMEDA Takayuki; MATSUMOTO Yosuke; EBIHARA Yusuke; TAKADA Taku; VASSILIS Angelopoulos
  A new self-consistent and kinetic model for ring current particles in the inner magnetosphere is presented. A closed set of nonlinear time evolution equations is derived that incorporates kinetic particle dynamics and self-consistent development of the electromagnetic field. The particle transport is described by a five-dimensional collisionless drift kinetic equation, in which particle trajectories are approximated by their guiding centers under the influence of a time-dependent electromagnetic field. The time evolution of the electromagnetic field follows the Maxwell equations with the feedback from particles through electric currents. A numerical simulation code solving the system of equations in a global inner magnetosphere in three spatial dimensions(or five dimensions in phase space) is developed. It is demonstrated that the propagation of low-frequency plasma waves can successfully be described by the developed model. It is also found that the self-consistent coupling could affect the transport of energetic particles especially at low energies as well as the intensity and spatial distribution of field-aligned currents. These preliminary results suggest the importance of the self-consistent coupling in the global development of geomagnetic storms. Our approach extends the capability of modeling storm time phenomena occurring in the inner magnetosphere. These include sudden commencements(SCs), substorms, and ULF waves, and other associated phenomena.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Nagoya University, 20340134
• Study of Vlasov simulation techniques for next-generation supercomputers
  Grants-in-Aid for Scientific Research
  2009 - 2010
  UMEDA Takayuki
  We study numerical schemes for the first-principle Vlasov code as a second-next-generation computer simulation technique of space plasma. We developed numerical algorithms for solving the collisionless Boltzmann (Vlasov) equation which is a hyper-dimensional conservation law. The new simulation code is parallelized for scalar massively parallel computers and has achieved more than 80% parallel efficiency on more than 1,000 CPU cores. The new code is applied to various multi-scale processes in space plasma. The numerical results imply the existence of cross-scale coupling between fluid scale and particle scale.
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (B), Nagoya University, Principal investigator, Competitive research funding, 21740352
• Study of Revolutionary Vlasov simulation techniques
  Grants-in-Aid for Scientific Research
  2007 - 2008
  UMEDA Takayuki
  次世代宇宙プラズマシミュレーション技術である第一原理ブラソフコードの研究開発を行った。連続体の多次元発展方程式である無衝突ボルツマン(ブラソフ)方程式を高精度かつ安定に解き進めることかできる数値解法を開発し、宇宙プラズマ中の様々なマルチスケール現象に対してベンチマークテストを行った。その結果、新たに開発したコードは従来のブラソフコードよりもはるかにロバストであることがわかった。次世代スーパーコンピュータに向けた高速化および超並列化が今後の課題である
  Japan Society for the Promotion of Science, Grant-in-Aid for Young Scientists (Start-up), Nagoya University, Principal investigator, Competitive research funding, 19840024
• 開放系プラズマモデルによる静電孤立波の計算機実験
  科学研究費助成事業
  2001 - 2003
  梅田 隆行
  本年度の研究によって得られた以下の成果を国内・国際会議および学会誌に論文発表をしたとともに、膨大なデータの保存のためにハードディスク等を購入した。
  1.二次元及び、三次元電磁粒子コードにおいて、電流密度の計算を従来の方法より高速に行う計算アルゴリズムを開発し、コンピュータ科学雑誌に発表した。この手法を用いて、数値的熱雑音がより少なく計算効率の良い三次元電磁粒子コードを新たに開発した。
  2.従来電磁界を無視した静電粒子コードを用いて行われていた電子ビーム不安定性の計算機実験を、世界に先駆けて電磁粒子モデルへ拡張した。背景磁場と二次元構造を持つ静電孤立波の磁場に垂直な電界を受けて電子がE×Bドリフトすることにより二次元静電孤立波の垂直方向の端において電流が生じ、二次元静電孤立波の周辺に電磁界が励起することを明らかにした。また、計算機実験結果がオーロラ領域で観測されている静電孤立波に伴った電磁界成分の特性とよく一致していることを示した。さらに、孤立した静電ポテンシャル内において形成された電流構造が電磁波の放射源となり得るという新しい物理過程について明らかにした。これは、従来の電子ビームや連続的な波動からの直接的な電磁放射とは全く異なる物理過程であり、宇宙プラズマ物理のみならず、実験室プラズマや天体プラズマへの適応が可能な新たな電磁放射過程である。この成果を、2件の国内会議、国際測地学・地球物理学連合会札幌大会及びアメリカ地球物理学連合秋大会において研究発表を行い、論文としてJGR誌に発表した。また、上記の最新の結果を含む静電孤立波の国内外の研究に関して、実験室及び宇宙空間におけるプラズマ実験に関する国際研究集会において招待講演を行った。
  日本学術振興会, 特別研究員奨励費, 京都大学, 01J03821

• The FDTD analysis method
  Patent right, Takayuki UMEDA; Harune Sekido, 国立大学法人東海国立大学機構
  特願2022-082029, 19 May 2022
  特開2023-170345, 01 Dec. 2023
• METHOD FOR ANALYZING MOTION OF CHARGED PARTICLES BASED ON RELATIVISTIC EQUATION OF MOTION
  Patent right, 梅田 隆行, 国立大学法人東海国立大学機構
  特願2022-032260, 03 Mar. 2022
  特開2023-128129, 14 Sep. 2023
• METHOD OF ANALYZING CHARGED PARTICLE KINETICS BY LORENTZ FORCE OF MAGNETIC FIELD
  Patent right, Takayuki UMEDA, Nagoya University
  特願2017-118277, 16 Jun. 2017
  特開2019-003457, 10 Jan. 2019

• 宇宙プラズマの第一原理ブラソフシミュレーション
  Mar. 2017
  Lecturer
  神戸大学計算科学教育センター
  KOBE HPC Spring School 2017
  神戸大学計算科学教育センター
• 宇宙プラズマの第一原理ブラソフコードの性能評価
  Dec. 2015
  Lecturer
  高度情報科学技術研究機構
  平成27年度「京」における高速化ワークショップ
  秋葉原UDX
  Graduate students, Researchers, Scientific organization, Company
  宇宙プラズマの第一原理ブラソフコードの性能評価
• 京コンピュータを用いた宇宙プラズマの第一原理ブラソフシミュレーション
  Oct. 2013
  Lecturer
  サイエンティフィック・システム研究会
  科学技術計算分科会 2013年度会合「ペタからエクサへの課題」
  ホテルオークラ神戸
  Teachers, Researchers, General, Scientific organization, Company, Governmental agency
• 宇宙科学とコンピュータシミュレーション
  Aug. 2010
  Lecturer
  高知工業高等専門学校
  STP教育研究セミナー公開講座
  高知工業高等専門学校
• STPシミュレーションの過去・現在・未来
  Sep. 2009
  Lecturer
  名古屋大学太陽地球環境研究所
  宇宙地球惑星科学若手会 2009年夏の学校
  伊勢青少年研修センター
  College students, Graduate students, Researchers

• 青山学院大学ら8大学の共同研究グループが「大型レーザー装置で実験室に宇宙プラズマ衝撃波を生成 -- 宇宙線の生成メカニズム解明に向け新たな研究手段を確立 -- 」
  30 Aug. 2020
  青山学院大学
  [Internet]