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Hagiwara, Hiroki; Takaku, Atsushi*; Sagawa, Hiroshi*; Kanno, Futoshi*; Ito, Azusa; Ando, Taichi*; Ichihara, Masatsugu*; Watanabe, Yusuke; Koarai, Kazuma; Kato, Jun; et al.
Proceedings of Waste Management Symposia 2026 (WM2026) (Internet), 7 Pages, 2026/03
Kato, Taichi*; Shiihara, Yoshinori*; Mori, Hideki*; Tsuru, Tomohito; Matsunaka, Daisuke*
Zairyo, 75(2), p.109 - 115, 2026/02
Machine-learning-based molecular dynamics (ML-MD) has emerged as a promising approach to resolving the trade-off between accuracy and computational cost in atomic simulations. The most conventional method in ML-MD, total energy learning (TEL), trains models by matching the sum of predicted atomic energies to the total energy of the system. However, because calculating total energy requires information from all atoms in the system, TEL poses limitations for flexible data refinement. To address this issue, we have developed atomic energy learning (AEL), which enables atomic level data selection by directly using each atom's energy as training data. As a fundamental study, we compare AEL and TEL using datasets based on the Embedded Atom Method (EAM). The results demonstrate the effectiveness of selective data sampling in controlling model accuracy and reveal the advantage of AEL in evaluating atomic energies near defects through targeted data selection.
Sakasegawa, Hideo; Nakajima, Motoki*; Kato, Taichiro*; Nozawa, Takashi*; Ando, Masami*
Materials Today Communications (Internet), 40, p.109659_1 - 109659_8, 2024/08
Times Cited Count：1 Percentile：5.77(Materials Science, Multidisciplinary)Nanometric oxide particles play an important role in improving the creep property of Oxide Dispersion Strengthened (ODS) steels. In our previous research, we examined a microstructural feature known as prior particle boundary (PPB). PPB refers to the surface of mechanically alloyed (MA) powders before consolidation. We revealed that the ODS steel with fine PPBs produced from smaller MA powders, exhibited shorter creep rupture times, compared to that with coarse PPBs produced from larger MA powders. The size of MA powders had an impact on the creep property. In this study, we examined the shape of MA powders, which were non-spherical shapes. Such shapes have the potential to induce anisotropic creep behavior. We conducted small punch creep tests on specimens with two different orientations to study the possible anisotropy. The results revealed that the creep rupture times varied depending on the orientation of specimen, thus indicating anisotropic creep property.
Kato, Taichiro; Ohata, Mitsuru*; Nogami, Shuhei*; Tanigawa, Hiroyasu
Fusion Engineering and Design, 109-111(Part B), p.1631 - 1636, 2016/11
Times Cited Count：13 Percentile：69.12(Nuclear Science & Technology)Plastic deformability of material shows general tendency to decrease due to become hard and brittle. Also, the plastic deformability tends to decrease as the stress triaxiality of a parameter to evaluate the magnitude of plastic constraint increases. Therefore, it is necessary to accurately understand the ductility loss limit of RAFM in order to conduct the structural design assessment of a fusion reactor demo blanket. In this study, plastic deformability of RAFM was evaluated the impacts of stress triaxiality on variation of tensile specimen shape and testing conditions. In the results, the fracture was defined as not the point of macro-crack but that of micro-crack. It was confirmed that the true strain rate significantly increases in the vicinity of the point of micro-crack. The relationships between the fracture ductile and stress triaxiality of the full size tensile specimen and the miniature size one were shown on the single curve regardless of the specimen size.
Ito, Sayuri; Fujimaki, Shu; Kato, Taichi*; Otake, Norikuni*; Sueyoshi, Kuni*; Oyama, Takuji*
Nitrogen assimilation in plants, p.205 - 214, 2010/07
