※ 半角英数字
 年 ~ 
検索結果: 326 件中 1件目~20件目を表示


Initialising ...



Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...



Metalloid substitution elevates simultaneously the strength and ductility of face-centered-cubic high-entropy alloys

Wei, D.*; Wang, L.*; Zhang, Y.*; Gong, W.; 都留 智仁; Lobzenko, I.; Jiang, J.*; Harjo, S.; 川崎 卓郎; Bae, J. W.*; et al.

Acta Materialia, 225, p.117571_1 - 117571_16, 2022/02

Recently-developed high-entropy alloys (HEAs) containing multiple principal metallic elements have ex-tended the compositional space of solid solutions and the range of their mechanical properties. Here we show that the realm of possibilities can be further expanded through substituting the constituent metals with metalloids, which are desirable for tailoring strength/ductility because they have chemical interactions and atomic sizes distinctly different from the host metallic elements. Specifically, the metalloid substitution increases local lattice distortion and short-range chemical inhomogeneities to elevate strength, and in the meantime reduces the stacking fault energy to discourage dynamic recovery and encourage defect accumulation via partial-dislocation-mediated activities. These impart potent dislocation storage to improve the strain hardening capability, which is essential for sustaining large tensile elongation. As such, metalloid substitution into HEAs evades the normally expected strength-ductility trade-off, enabling an unusual synergy of high tensile strength and extraordinary ductility for these single-phase solid solutions.


Development of a supplementary outboard side thruster system for dynamic positioning control of autonomous surface vehicle

加藤 哲*; 川村 大和*; 田原 淳一郎*; 馬場 尚一郎*; 眞田 幸尚; 藤井 俊*

International Journal of Offshore and Polar Engineering, 31(3), p.316 - 324, 2021/09




Invention of automatic movement and dynamic positioning control method of unmanned vessel for mud mining

藤井 俊*; 加藤 哲*; 川村 大和*; 田原 淳一郎*; 馬場 尚一郎*; 眞田 幸尚

Proceedings of 26th International Symposium on Artificial Life and Robotics (AROB 26th 2021), p.280 - 285, 2021/01



Development of side thruster system for ASV

加藤 哲*; 川村 大和*; 田原 淳一郎*; 馬場 尚一郎*; 眞田 幸尚

Proceedings of the 30th (2020) International Ocean and Polar Engineering Conference (ISOPE 2020) (USB Flash Drive), p.1255 - 1260, 2020/10

This paper describes the development of side thruster system can keep the heading direction for ASV (Autonomous Surface Vehicle). At present, JAMSTEC, JAEA, and TUMSAT are jointly working on the investigation of radioactivity in mud deposited in estuaries in Fukushima Prefecture, Japan. The main objective of this project is unmanned mud collect using the ASV. We developed and controlled the side thruster system for applying ASV to mud collecting operation. As the result of the bollard test, turn and parallel movement test, we confirmed that it can maintain the heading direction for the ASV.


Visualizing cation vacancies in Ce:Gd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$ scintillators by gamma-ray-induced positron annihilation lifetime spectroscopy

藤森 公佑*; 北浦 守*; 平 義隆*; 藤本 將輝*; Zen, H.*; 渡邊 真太*; 鎌田 圭*; 岡野 泰彬*; 加藤 政博*; 保坂 将人*; et al.

Applied Physics Express, 13(8), p.085505_1 - 085505_4, 2020/08

 被引用回数:1 パーセンタイル:24.67(Physics, Applied)

CeドープGd$$_{3}$$Al$$_{2}$$Ga$$_{3}$$O$$_{12}$$(Ce:GAGG)シンチレーターにおける陽イオン空孔の存在を明らかにするために、ガンマ線誘起陽電子消滅寿命測定(GiPALS)法による測定を行った。GAGGおよびCe:GAGGのGiPALSスペクトルに現れる成分は、バルク中と欠陥に捕獲された状態の陽電子消滅であり、その結果2つの指数減衰成分で構成されている。Ce:Y$$_{3}$$Al$$_{5}$$O$$_{12}$$に関する研究から、欠陥に関連する構造はAl/Ga-Oの複空孔に起因するものであることが示唆された。この成分は、Ce, Mg:GAGGの方が小さくなり、その傾向はリン光の原因である浅い電子トラップの抑制と相関していた。酸素空孔は、Al/Ga空孔の電荷を補う役割をしている。欠陥に関連した構造における寿命は、Mg共ドーピングによって大幅に変化し、これは、酸素空孔とともに、Al/GaサイトでのMg$$^{2+}$$イオンとの集合体を考慮することで理解され、その結果、空孔クラスターが形成された。


Temporal change in radiological environments on land after the Fukushima Daiichi Nuclear Power Plant accident

斎藤 公明; 三上 智; 安藤 真樹; 松田 規宏; 木名瀬 栄; 津田 修一; 佐藤 哲朗*; 関 暁之; 眞田 幸尚; Wainwright-Murakami, Haruko*; et al.

Journal of Radiation Protection and Research, 44(4), p.128 - 148, 2019/12

Massive environmental monitoring has been conducted continuously after the Fukushima accident with different monitoring methods having different features together with migration studies of radiocesium in diverse environments. At three months after the accident, multiple radionuclides were detected at many places; while it was confirmed that radiocesium was most important from the viewpoint of long-term exposures. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2-3 on average. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of massive car-borne survey data. Some trials were performed to integrate different types of contamination maps to obtain an integrated map of better quantity. Annual external exposure doses for residents who would return to their home were estimated to less than a few mSv as a whole. The environmental data and knowledge have been provided for diverse-spectrum of people in different ways.


Isotope-selective microscale imaging of radioactive Cs without isobaric interferences using sputtered neutral mass spectrometry with two-step resonant ionization employing newly-developed Ti:Sapphire lasers

坂本 哲夫*; 森田 真人*; 金成 啓太*; 富田 英生*; Sonnenschein, V.*; 齊藤 洸介*; 大橋 雅也*; 加藤 弘太郎*; 井口 哲夫*; 河合 利秀*; et al.

Analytical Sciences, 34(11), p.1265 - 1270, 2018/11

 被引用回数:7 パーセンタイル:39.71(Chemistry, Analytical)

Characterization of radionuclides in Fukushima is important to determine their origins and current state in the environment. Radionuclides exist as fine particles and are mixed with other constituents. A measurement method with both micro-imaging capability and highly selective element detection is necessary to analyze these particles. We developed such an imaging technique using a time-of-flight secondary ion mass spectrometry and wavelength tunable Ti:Sapphire lasers for resonance ionization of target elements without mass interference. This is called resonant laser ionization sputtered neutral mass spectrometry. The instrument has high lateral resolution and higher ionization selectivity using two-step resonance excitation of Cs with two lasers at different wavelengths. Optimization of the wavelength for resonance ionization using a Cs compound was performed, and a real environmental particle containing radioactive Cs was analyzed. Isotope images of three kinds of Cs were successfully obtained without interfere from Ba isotopes for the first time.


Investigation of hydrogen gas generation by radiolysis for cement-solidified products of used adsorbents for water decontamination

佐藤 淳也; 菊地 博*; 加藤 潤; 榊原 哲朗; 松島 怜達; 佐藤 史紀; 小島 順二; 中澤 修

QST-M-8; QST Takasaki Annual Report 2016, P. 62, 2018/03

福島第一原子力発電所における多核種除去設備から発生している廃吸着材は、多量の放射性核種を含有しており、処分のために発生した固化体への放射線影響が懸念されている。本件は、廃吸着材の模擬物をセメント固化した試料において放射線分解によって発生する水素ガス量の調査を目的として実施した。チタン酸塩, 酸化チタン, フェロシアン化物, キレート樹脂及び樹脂系吸着材を対象として、セメント固化材(普通ポルトランドセメント及び高炉スラグセメント)を用いて固化試料を作製した。量子科学技術研究開発機構高崎量子応用研究所のコバルト照射施設を利用して$$gamma$$線の照射試験を行い、セメント固化試料からの水素ガス発生を調査した。試験の結果、セメント固化試料から発生した水素ガス量を求め、水素ガス発生のG値を算出することができた。



加藤 潤; 中川 明憲; 谷口 拓海; 榊原 哲朗; 中澤 修; 目黒 義弘

JAEA-Review 2017-015, 173 Pages, 2017/07




The Hydrogen gas generation by electron-beam irradiation from ALPS adsorbents solidified by several inorganic materials

佐藤 淳也; 鈴木 眞司*; 加藤 潤; 榊原 哲朗; 目黒 義弘; 中澤 修

QST-M-2; QST Takasaki Annual Report 2015, P. 87, 2017/03



The Hydrogen gas generation by gamma-ray irradiation from ALPS adsorbents solidified by several inorganic materials

佐藤 淳也; 鈴木 眞司*; 加藤 潤; 榊原 哲朗; 目黒 義弘; 中澤 修

QST-M-2; QST Takasaki Annual Report 2015, P. 88, 2017/03



Progress of the general control system for the Materials and Life Science Experimental Facility in J-PARC

酒井 健二; 大井 元貴; 渡辺 聡彦; 甲斐 哲也; 加藤 裕子; 明午 伸一郎; 高田 弘

JAEA-Conf 2015-002, p.593 - 598, 2016/02



超深地層研究所計画 年度報告書(2014年度)

濱 克宏; 見掛 信一郎; 石橋 正祐紀; 笹尾 英嗣; 桑原 和道; 上野 哲朗; 大貫 賢二*; 別府 伸治; 尾上 博則; 竹内 竜史; et al.

JAEA-Review 2015-024, 122 Pages, 2015/11


日本原子力研究開発機構東濃地科学センターでは、「地層処分技術に関する研究開発」のうち深地層の科学的研究(地層科学研究)の一環として、結晶質岩(花崗岩)を対象とした超深地層研究所計画を進めている。本計画は、「第1段階; 地表からの調査予測研究段階」、「第2段階; 研究坑道の掘削を伴う研究段階」、「第3段階; 研究坑道を利用した研究段階」の3段階からなり、2014年度は、2014年2月における深度500mステージの研究坑道の掘削工事の完了に伴い、超深地層研究所計画における深度500mまでの第2段階の調査研究を一旦終了し、これまで実施してきた各種モニタリングを含め、物質移動試験や再冠水試験等の第3段階の調査研究を進めた。本報告書は、2014年度に実施した調査研究、施設建設、共同研究等の成果を取りまとめたものである。


Soft X-ray laser observation of femtosecond-laser-driven ablation of tungsten

錦野 将元; 長谷川 登; 石野 雅彦; 越智 義浩; 河内 哲哉; 山極 満; 加藤 義章*

Chinese Optics Letters, 13(7), p.070002_1 - 070002_3, 2015/07

 被引用回数:1 パーセンタイル:8.29(Optics)

Ablation dynamics of tungsten irradiated with a 70-fs laser pulse is investigated with X-ray interferometry and X-ray imaging using 13.9 nm soft X-ray laser of 7 ps pulse duration. The evolution of high density ablation front of tungsten is presented. The ablation front expands to around 120 nm above the original target surface at 160 ps after fs-laser irradiation with the expansion speed of approximately 750 m/s. These results will provide important data for understanding ablation properties of W, which is a candidate material of the first wall of magnetic confinement fusion reactors.


Development of prediction technology of two-phase flow dynamics under earthquake acceleration, 16; Experimental and numerical study of pressure fluctuation effects on bubble motion

加藤 由幹; 吉田 啓之; 横山 諒太郎*; 金川 哲也*; 金子 暁子*; 文字 秀明*; 阿部 豊*

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 8 Pages, 2015/05

In this study, visualization experiment for the bubbly flow in a horizontal pipe excited by oscillation acceleration was performed to understand bubbly flow behavior under earthquake acceleration. Liquid pressure was also measured at upstream and downstream of the test section. In addition, to consider detailed effects of pressure gradient on bubble motion, numerical simulation of two-phase flow in horizontal pipe with vibration was performed by a detailed two-phase flow simulation code with an advanced interface tracking method: TPFIT. Based on observed images and calculated results, bubble velocity was evaluated. It was confirmed that the pressure gradient amplitude increased with the increase of the frequency of the table. In addition, it was observed that the bubble velocity amplitude also increases with the increase of the frequency of the table. It was concluded that the bubble motion was strongly affected by the pressure gradient in the test section.


Spatial distributions of radionuclides deposited onto ground soil around the Fukushima Dai-ichi Nuclear Power Plant and their temporal change until December 2012

三上 智; 前山 健司*; 星出 好史*; 坂本 隆一*; 佐藤 昭二*; 奥田 直敏*; Demongeot, S.*; Gurriaran, R.*; 上蓑 義朋*; 加藤 弘亮*; et al.

Journal of Environmental Radioactivity, 139, p.320 - 343, 2015/01

 被引用回数:70 パーセンタイル:94.06(Environmental Sciences)

Comprehensive investigations have been conducted on the land environment affected by the Fukushima Dai-ichi Nuclear Power Plant accident. Distribution maps of Cs-134, Cs-137, and Ag-110m deposition density as of March, September, and December 2012, were constructed according to monitoring results obtained at nearly a thousand locations. Little temporal change of the deposited radionuclides was observed during the nine months from March to December 2012. Weathering effects especially horizontal mobility, during this time were not noticeable. Spatial characteristics in the ratios of Cs-134/Cs-137 and Ag-110m/Cs-137 that deposited on ground were observed by investigations in the Tohoku and Kanto areas. The elaborate deposition maps of Cs-134 and Cs-137 as of September 2012, and those as of December 2012, were constructed using the relationship between the air dose rate and the deposited activity per unit area.


High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; 神門 正城; Esirkepov, T. Z.; Faenov, A. Y.*; Pikuz, T. A.*; 河内 哲哉; 匂坂 明人; Koga, J. K.; 森 道昭; 川瀬 啓悟*; et al.

RAL-TR-2015-025, P. 22, 2015/00

We provide a description of experiments performed with the J-KAREN and Astra Gemini lasers where we discovered a new regime of relativistic high-order harmonic generation by multi-terawatt femtosecond lasers in gas targets. The results were explained using particle-in-cell simulations and catastrophe theory. Our work paves the way towards a bright coherent X-ray source based on compact lasers and accessible, repetitive, and debris-free gas jet targets. Such a source will be crucial for fundamental research and numerous applications requiring pumping, probing, imaging of microscopic objects and for attosecond science.


High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; 神門 正城; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T. A.*; 河内 哲哉; 匂坂 明人; et al.

New Journal of Physics (Internet), 16(9), p.093003_1 - 093003_30, 2014/09

 被引用回数:25 パーセンタイル:81.51(Physics, Multidisciplinary)

We present a detailed description of our discovery of a new regime of high-order harmonic generation, including experimental data, simulations, and description of new harmonic generation mechanism. The harmonics are generated by multi-terawatt relativistic-irradiance ($$>$$ 10$$^{18}$$ W/cm$$^2$$) femtosecond ($$approx$$ 30-50 fs) lasers focused to gas jet targets. According to our model, the harmonics are produced by sharp, structurally stable, oscillating electron spikes at the joint of boundaries of wake and bow waves excited by the laser pulse.


Non-volcanic seismic swarm and fluid transportation driven by subduction of the Philippine Sea slab beneath the Kii Peninsula, Japan

加藤 愛太郎*; 雑賀 敦; 武田 哲也*; 岩崎 貴哉*; 松澤 暢*

Earth, Planets and Space (Internet), 66, p.86_1 - 86_8, 2014/08

 被引用回数:17 パーセンタイル:54.31(Geosciences, Multidisciplinary)



Preparation of tungsten carbide nanoparticles by ion implantation and electrochemical etching

加藤 翔; 八巻 徹也; 山本 春也; 箱田 照幸; 川口 和弘; 小林 知洋*; 鈴木 晶大*; 寺井 隆幸*

Nuclear Instruments and Methods in Physics Research B, 314, p.149 - 152, 2013/11

 被引用回数:0 パーセンタイル:0.01(Instruments & Instrumentation)

本研究では、イオン注入と電気化学エッチングを組合せて、グラッシーカーボン基板上に炭化タングステン(WC)のナノ微粒子を作製した。実験では、100keV W$$^+$$をグラッシーカーボン基板に照射して注入試料を作製した後、水酸化ナトリウム水溶液中で注入試料の表面をアノード酸化によりエッチングした。試料の分析にはX線光電子分光(XPS), ラザフォード後方散乱分析(RBS), 透過型電子顕微鏡(TEM)を用いた。XPS, RBSの結果から、試料中でWCが形成されていたことと、電気化学エッチングによってその高濃度導入面が表面に露出したことが確認できた。断面TEMによって直径約10nmのナノ微粒子が表層に存在している様子が観察された。

326 件中 1件目~20件目を表示