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Shi, W.*; 町田 昌彦; 岡本 孝司*; Luo, X.*; Feng, W.*; Liu, X.*
Reliability Engineering & System Safety, 272, Part1, p.112538_1 - 112538_18, 2026/08
深刻な原子力事故時における緊急対応の信頼性は、放射性線源分布をリアルタイムで確実に監視できるかどうかに大きく依存する。しかし、この安全機能は、監視の死角を生じさせる物理的制約や動的な放出を追跡するには静的手法が不十分であるという問題によって大きく制約されている。本研究では、線源推定の信頼性およびロバスト性を向上させるため、時間正則化を導入したLASSO回帰に基づく動的再構成フレームワークを提案する。具体的には、スライディングウィンドウ型の時間ペナルティ機構を導入し、時間ステップ間の線源変化に対して
ノルム制約を課すことで、物理的連続性を確保する。また、放射線遮蔽や時間的に変動する強度によるバイアスを補正するため、寄与行列および測定ベクトルを正規化した。検証には、内部遮蔽を有する二室モデルを用い、PHITS(モンテカルロシミュレーション)を用いて実施した結果、遠隔測定データから動的線源を高精度に再構成できることが示された。時間正則化は、空間エイリアシングを抑制し、状況認識能力を向上させる。スライディングウィンドウ幅
(正則化なし)の場合、ホットスポット位置は大きく変動し、平均絶対誤差の変動量は約
であった。一方、
では空間的一貫性が改善され、誤差変動量は
程度まで低減した。比較解析の結果、精度と計算コストのバランスの観点から
が最適であることが示された。本研究は、困難な条件下においても線源位置および強度を高精度で追跡可能とする、動的ハザード評価のためのより信頼性の高い手法を提示するものである。提案手法は、原子力施設における緊急時管理のレジリエンスと安全性を向上させる意思決定支援ツールとしての活用が期待される。
Li, X.*; Zhu, R.*; Xin, J.*; Luo, M.*; Shang, S.-L.*; Liu, Z.-K.*; Yin, C.*; 舟越 賢一*; Dippenaar, R. J.*; 肥後 祐司*; et al.
CALPHAD; Computer Coupling of Phase Diagrams and Thermochemistry, 84, p.102641_1 - 102641_6, 2024/03
被引用回数：0 パーセンタイル：0.00(Thermodynamics)The phase transformations and pressure-volume dependencies of the Ti-45Al alloy with respect to pressure have been investigated by means of in-situ observation using multi anvil-type high-pressure devices and synchrotron radiation. Under hydrostatic compression from 0 to 10.1 GPa, about 2.3 vol. % of 
transforms continuously to 
2. Lattice parameters as well as volume fractions of these two phases have been determined as a function of pressure. Bulk moduli estimated using Birch-Murnaghan's equation of state are 148 GPa for the phase, 138 GPa for the 2 phase, and 149 GPa for their two-phase mixture of Ti-45Al alloy. First-principles have also applied to investigate bulk moduli of two single phases, and the deviation between calculations and measurements is discussed and attributed to mainly phase transformation. The presently study provides useful insights into thermodynamics of 2 and phases under high pressure.
Li, B.; Luo, X. H.*; Wang, H.*; Ren, W. J.*; Yano, S.*; Wang, C.-W.*; Gardner, J. S.*; Liss, K.-D.*; Miao, P.*; Lee, S.-H.*; et al.
Physical Review B, 93(22), p.224405_1 - 224405_6, 2016/06
被引用回数：72 パーセンタイル：89.40(Materials Science, Multidisciplinary)Competition between ferromagnetic and antiferromagnetic phases on frustrated lattices in hexagonal Laves phase compound Hf
Ta
Fe is investigated by using neutron diffraction as a function of temperature and magnetic fields and density-functional-theory calculations. At 325 K, the compound orders into the 120
frustrated antiferromagnetic state with well-reduced magnetic moment and an in-plane lattice contraction simultaneously sets in. With further cooling down, however, the accumulated distortion in turn destabilizes this susceptible frustrated structure. The frustration is completely relieved at 255 K when the first-order transition to the ferromagnetic state takes place, where a colossal negative volumetric thermal expansion, 
/K, is obtained. Meanwhile, the antiferromagnetic state can be suppressed by few Tesla magnetic fields, which results in a colossal positive magnetostriction. Such delicate competition is attributed to the giant magnetic fluctuation inherent in the frustrated antiferromagnetic state. Therefore, the magnetoelastic instability is approached even under a small perturbation.
Ding, F.*; Luo, G.-N.*; Pitts, R.*; Litnovsky, A.*; Gong, X.*; Ding, R.*; Mao, H.*; Zhou, H.*; Wampler, W. R.*; Stangeby, P. C.*; et al.
Journal of Nuclear Materials, 455(1-3), p.710 - 716, 2014/12
被引用回数：31 パーセンタイル：88.77(Materials Science, Multidisciplinary)A movable material probe system (Material and Plasma Evaluation System: MAPES) with an independent pumping system and a sample exchange chamber has been developed and installed on a horizontal port of the EAST tokamak for studies of plasma material interaction (PMI). In the 2012 experimental campaign, deposition and erosion were studied for three samples: mock-up of the outer first wall panels (FWPs) in ITER, castellated tungsten, and molybdenum mirrors. The FWPs with carbon deposition layer were exposed to helium plasmas. The maximum erosion rate of the carbon was valuated to be 8 nm/s. The castellated tungsten with rectangular cells and roof-like shaped cells was exposed to deuterium plasmas to compare amount of deposits on the gap surface. The amount of carbon and boron impurities on the gap surface of the roof-like shaped cells were reduced to less than 30% compared with that of the rectangular cells. The molybdenum mirrors of which protective ducts are installed in front were exposed to deuterium plasmas in order to investigate effects of length of the ducts. It was found that the reflectivity of the mirrors with 60 mm-long protective ducts is kept the initial reflectivity.
