3D reconstruction technologies and challenges for decommissioning work of Fukushima Daiichi Nuclear Power Station

Hanari, Toshihide; Nakamura, Keita*; Imabuchi, Takashi; Kawabata, Kuniaki

Keisoku To Seigyo (Internet) , 65(6), p.438 - 443, 2026/06

https://doi.org/10.11499/sicejl.65.438

no abstracts in English

Specific heat anomalies and local symmetry breaking in (anti-)fluorite materials; A Machine learning molecular dynamics study

Kobayashi, Keita; Nakamura, Hiroki; Okumura, Masahiko; Itakura, Mitsuhiro; Machida, Masahiko

Journal of Chemical Physics, 162(24), p.244508_1 - 244508_11, 2025/06

https://doi.org/10.1063/5.0262059

The specific heat anomaly in (anti-)fluorite structures was analyzed using machine learning molecular dynamics (MLMD) methods. By employing the Farthest Point Sampling method and the Bootstrap method, first-principles training data were efficiently generated, and machine learning potentials were created for thorium dioxide (fluorite structure) and lithium oxide (anti-fluorite structure). As a result, the MLMD method accurately reproduced the reported thermal properties of thorium dioxide and lithium oxide. These materials exhibit a specific heat anomaly at high temperatures due to sublattice disordering. However, the details are complex and not fully understood. In this study, by applying a local order parameter methodology, which has been used in the analysis of liquid-liquid phase transitions, we revealed that the anomalous specific heat in (anti-)fluorite structures can be interpreted as a consequence of local symmetry breaking.

Image selection method from image sequence to improve computational efficiency of 3D reconstruction; Application of fixed threshold to remove redundant images

Hanari, Toshihide; Nakamura, Keita*; Imabuchi, Takashi; Kawabata, Kuniaki

Journal of Robotics and Mechatronics, 36(6), p.1537 - 1549, 2024/12

https://doi.org/10.20965/jrm.2024.p1537

This paper describes three-dimensional (3D) reconstruction processes introducing the image selection method for efficiently generating a 3D model from an image sequence. To obtain suitable images for efficient 3D reconstruction, we tried to apply the image selection method to remove the redundant images in the image sequence. By the proposed method, the suitable images were selected from the image sequence based on optical flow measures and a fixed threshold. As a result, the proposed method can reduce the computational cost for the 3D reconstruction processes based on the image sequence acquired by the camera. We confirmed that the computational cost of the 3D reconstruction processes can reduce while keeping the 3D reconstruction accuracy at a constant level.

Integration of multiple dense point clouds based on estimated parameters in photogrammetry with QR code for reducing computation time

Nakamura, Keita*; Baba, Keita*; Watanobe, Yutaka*; Hanari, Toshihide; Matsumoto, Taku*; Imabuchi, Takashi; Kawabata, Kuniaki

Artificial Life and Robotics, 29(4), p.546 - 556, 2024/09

https://doi.org/10.1007/s10015-024-00966-3

Investigation of the influence of the magnitude of camera vibration on 3D reconstruction results by photogrammetry based on simulation

Nakamura, Keita*; Hanari, Toshihide; Imabuchi, Takashi; Kawabata, Kuniaki

Proceedings of 2024 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 2024), p.7 - 8, 2024/07

Photogrammetry is a technique for 3D reconstruction of target objects from multiple images shot of the object. In the case of actual photography, the object may not be reconstructed due to the inability to shoot images suitable for photogrammetry because of vibration in the camera's angle of view of the object. Therefore, we implement this vibration by using random numbers and verify the influence of the magnitude of the vibration on the reconstruction result obtained by photogrammetry. The verification results show the relationship between the magnitude of the vibration and the success rate of 3D reconstruction.

Estimated camera trajectory-based integration among local 3D models sequentially generated from image sequences by SfM-MVS

Matsumoto, Taku; Hanari, Toshihide; Kawabata, Kuniaki; Nakamura, Keita*; Yashiro, Hiroshi*

Artificial Life and Robotics, 29(2), p.358 - 371, 2024/05

https://doi.org/10.1007/s10015-024-00949-4

Integration of multiple partial point clouds based on estimated parameters in photogrammetry with QR codes

Baba, Keita*; Watanobe, Yutaka*; Nakamura, Keita*; Matsumoto, Taku; Hanari, Toshihide; Kawabata, Kuniaki

Proceedings of 29th International Symposium on Artificial Life and Robotics (AROB 29th 2024) (Internet), p.751 - 756, 2024/01

Machine learning molecular dynamics reveals the structural origin of the first sharp diffraction peak in high-density silica glasses

Kobayashi, Keita; Okumura, Masahiko; Nakamura, Hiroki; Itakura, Mitsuhiro; Machida, Masahiko; Urata, Shingo*; Suzuya, Kentaro

Scientific Reports (Internet), 13, p.18721_1 - 18721_12, 2023/11

https://doi.org/10.1038/s41598-023-44732-0

The first sharp peak diffraction peak (FSDP) in the structure factor of amorphous materials is thought to reflect the medium-range order structure in amorphous materials, and the structural origin of the FSDP has been a subject of ongoing debate. In this study, we employed machine learning molecular dynamics (MLMD) with nearly first-principles calculation accuracy to investigate the structural origin of the FSDP in high-density silica glass. First, we successfully reproduced various experimental data of high-density silica glass using MLMD. Furthermore, we revealed that the development (or reduction) of the FSDP in high-density silica glass is characterized by the deformation behavior of ring structures in Si-O covalent bond networks under compression.

Intruder configurations in Ne at the transition into the island of inversion; Detailed structure study of Ne

Wang, H.*; Yasuda, Masahiro*; Kondo, Yosuke*; Nakamura, Takashi*; Tostevin, J. A.*; Ogata, Kazuyuki*; Otsuka, Takaharu*; Poves, A.*; Shimizu, Noritaka*; Yoshida, Kazuki; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

https://doi.org/10.1016/j.physletb.2023.138038

Detailed -ray spectroscopy of the exotic neon isotope Ne has been performed using the one-neutron removal reaction from Ne. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder p-wave strength providing evidence of the breakdown of the N = 20 and N = 28 shell gaps. Only a weak, possible f-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large p-wave and small f-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain.

Integration of 3D environment models generated from the sections of the image sequence based on the consistency of the estimated camera trajectories

Matsumoto, Taku; Hanari, Toshihide; Kawabata, Kuniaki; Yashiro, Hiroshi*; Nakamura, Keita*

Proceedings of 22nd World Congress of the International Federation of Automatic Control (IFAC 2023) (Internet) , p.12107 - 12112, 2023/07