検索対象:     
報告書番号:
※ 半角英数字
 年 ~ 
 年
検索結果: 154 件中 1件目~20件目を表示

発表形式

Initialising ...

選択項目を絞り込む

掲載資料名

Initialising ...

発表会議名

Initialising ...

筆頭著者名

Initialising ...

キーワード

Initialising ...

使用言語

Initialising ...

発行年

Initialising ...

開催年

Initialising ...

選択した検索結果をダウンロード

論文

Elastic properties of nuclear pasta in a fully three-dimensional geometry

Xia, C.-J.*; 丸山 敏毅; 安武 伸俊*; 巽 敏隆*; Zhang, Y.-X.*

Physics Letters B, 839, p.137769_1 - 137769_5, 2023/04

 被引用回数:0 パーセンタイル:0.1(Astronomy & Astrophysics)

Realistic estimations on the elastic properties of neutron star matter are carried out with a large strain ($$varepsilon$$ $$_sim^{<}$$ 0.5) in the framework of relativistic-mean-field model with Thomas-Fermi approximation, where various crystalline configurations are considered in a fully three-dimensional geometry with reflection symmetry. Our calculation confirms the validity of assuming Coulomb crystals for the droplet phase above neutron drip density, which nonetheless does not work at large densities since the elastic constants are found to be decreasing after reaching their peaks. Similarly, the analytic formulae derived in the incompressible liquid-drop model give excellent description for the rod phase at small densities, which overestimates the elastic constants at larger densities. For slabs, due to the negligence on the variations of their thicknesses, the analytic formulae from liquid-drop model agree qualitatively but not quantitatively with our numerical estimations. By fitting to the numerical results, these analytic formulae are improved by introducing dampening factors. The impacts of nuclear symmetry energy are examined adopting two parameter sets, corresponding to the slope of symmetry energy L = 41.34 and 89.39 MeV. Even with the uncertainties caused by the anisotropy in polycrystallines, the elastic properties of neutron star matter obtained with L = 41.34 and 89.39 MeV are distinctively different, results in detectable differences in various neutron star activities.

論文

Corrosion fatigue crack growth behavior of a structurally gradient steel for high-speed railway axles

Ao, N.*; Zhang, H.*; Xu, H. H.*; Wu, S. C.*; Liu, D.*; 徐 平光; Su, Y. H.; Kang, Q. H.*; Kang, G. Z.*

Engineering Fracture Mechanics, 281, p.109166_1 - 109166_14, 2023/03

 被引用回数:0 パーセンタイル:0.01(Mechanics)

Considering the complex service environments that high-speed railway axles are subjected to, the fatigue crack growth (FCG) behavior of a structurally gradient axle steel with different pre-crack depths both in air and corrosive medium was investigated at a frequency of 5 Hz. The results indicated that in the high $$Delta$$$$K$$ region, FCG rate was dramatically accelerated by corrosion, but the gap narrows as $$Delta$$$$K$$ decreased. The accelerated corrosion FCG rate was a comprehensive result of the acceleration effect of the anodic dissolution, hydrogen-enhanced localized plasticity and the retardation effect of corrosion-induced crack-tip blunting. Despite the fact that the corrosion resistance gradually decreased as the pre-crack depth increased, the FCG rate in the corrosive medium gradually decreased. This was because fatigue loading played a more important role than corrosion in accelerating the corrosion FCG rate.

論文

Tensile overload-induced texture effects on the fatigue resistance of a CoCrFeMnNi high-entropy alloy

Lam, T.-N.*; Chin, H.-H.*; Zhang, X.*; Feng, R.*; Wang, H.*; Chiang, C.-Y.*; Lee, S. Y.*; 川崎 卓郎; Harjo S.; Liaw, P. K.*; et al.

Acta Materialia, 245, p.118585_1 - 118585_9, 2023/02

 被引用回数:1 パーセンタイル:44.11(Materials Science, Multidisciplinary)

The present study investigates the crystallographic-texture effects on the improved fatigue resistance in the CoCrFeMnNi high-entropy alloys (HEAs) with the full-size geometry of the ASTM Standards E647-99. We exploited X-ray nano-diffraction mapping to characterize the crystal-deformation levels ahead of the crack tip after stress unloading under both constant- and tensile overloaded-fatigue conditions. The crack-tip blunting-induced much higher deformation level was concentrated surrounding the crack-tip which delays the fatigue-crack growth immediately after a tensile overload. The predominant deformation texture orientation in the Paris regime was investigated, using electron backscatter diffraction and orientation distribution function analyses. The twinning formation-driven shear deformation gave rise to the development of the Goss-type texture within the plastic deformation regime under a tensile-overloaded-fatigue condition, which was attributed to enhance the crack deflection and thus the tensile induced crack-growth-retardation period in the CoCrFeMnNi HEA.

論文

Grain refinement in titanium prevents low temperature oxygen embrittlement

Chong, Y.*; Gholizadeh, R.*; 都留 智仁; Zhang, R.*; 井上 耕治*; Gao, W.*; Godfrey, A.*; 光原 昌寿*; Morris, J. W. Jr.*; Minor, A. M.*; et al.

Nature Communications (Internet), 14, p.404_1 - 404_11, 2023/02

チタンは格子間酸素によって脆化する。特に極低温では顕著な脆化挙動を示すため、チタンやその合金の製造において酸素含有量を厳しく管理する必要がある。この問題を解決するために、我々は結晶粒の微細化という構造戦略を提案した。77Kで非常に脆い粗粒の組織と比較して、Ti-0.3wt.%Oの超微細粒(UFG)組織(粒径$$sim$$2.0$$mu$$m)は、UFG組織特有の超高降伏強度を維持したまま均一延びを1桁上昇させることに成功した。UFG Ti-0.3wt.%Oにおけるこの特異な強度-延性相乗効果は、粒界凝集エネルギー向上に寄与する希薄な酸素の粒界偏析と優れたひずみ硬化能に寄与する$$<c+a>$$転位の活性化の複合効果によって達成された。この方法は、低温での高強度Ti-O合金の応用の可能性を高めるだけでなく、格子間固溶硬化による延性の低下を生じる他の合金系にも適用できる可能性がある。

論文

Hybridized propagation of spin waves and surface acoustic waves in a multiferroic-ferromagnetic heterostructure

Chen, J.*; 山本 慧; Zhang, J.*; Ma, J.*; Wang, H.*; Sun, Y.*; Chen, M.*; Ma, J.*; Liu, S.*; Gao, P.*; et al.

Physical Review Applied (Internet), 19(2), p.024046_1 - 024046_9, 2023/02

 被引用回数:0 パーセンタイル:0(Physics, Applied)

Coherent coupling in magnon based hybrid system has many potential applications in quantum information processing. Magnons can propagate in magnetically ordered materials without any motion of electrons, offering a unique method to build low-power-consumption devices and information channels free of heat dissipation. In this article, we demonstrate the coherent propagation of hybridized modes between spin waves and Love surface acoustic waves in a multiferroic BiFeO$$_{3}$$ and ferromagnetic La$$_{0.67}$$Sr$$_{0.33}$$MnO$$_{3}$$ based heterostructure. The magneto-elastic coupling enables a giant enhancement of strength of the hybridized mode by a factor of 26 compared to that of the pure spin waves. A short wavelength down to 250 nm is demonstrated for the hybridized mode, which is desirable for nanoscale acousto-magnonic applications. Our combined experimental and theoretical analyses represent an important step towards the coherent control in hybrid magnonics, which may inspire the study of magnon-phonon hybrid systems for coherent information processing and manipulation.

論文

Fatigue crack non-propagation behavior of a gradient steel structure from induction hardened railway axles

Zhang, H.*; Wu, S. C.*; Ao, N.*; Zhang, J. W.*; Li, H.*; Zhou, L.*; 徐 平光; Su, Y. H.

International Journal of Fatigue, 166, p.107296_1 - 107296_11, 2023/01

 被引用回数:0 パーセンタイル:0.01(Engineering, Mechanical)

Abnormal damages in railway axles can lead to a significant hazard to running safety and reliability. To this end, a surface treatment was selected to effectively inhibit fatigue crack initiation and growth. In this study, a single edge notch bending fatigue test campaign with artificial notches was conducted to elucidate the fatigue crack non-propagation behavior in railway S38C axles subjected to an induction hardening process. The fatigue cracking behavior in the gradient structure was revealed by optical microscopy, electron backscatter diffraction, and fractography. The microhardness distribution was measured using a Vickers tester. The obtained results show that the microhardness of the strengthening layer is nearly triple that of the matrix. Owing to the gradient microstructures and hardness, as well as compressive residual stress, the fatigue long crack propagates faster once it passes through the hardened zone (approximately 2.0 mm in the radial depth). Thereafter, local retarding (including deflection, branching, and blunting) of the long crack occurs because of the relatively coarse ferrite and pearlite in the transition region and matrix. Totally, this fatigue cracking resistance is reasonably believed to be due to the gradient microstructure and residual stress. These findings help to tailor a suitable detection strategy for maximum defects or cracks in railway axles.

論文

Experimental evidence for the significance of optical phonons in thermal transport of tin monosulfide

Wu, P.*; 村井 直樹; Li, T.*; 梶本 亮一; 中村 充孝; 古府 麻衣子; 中島 健次; Xia, K.*; Peng, K.*; Zhang, Y.*; et al.

New Journal of Physics (Internet), 25(1), p.013032_1 - 013032_11, 2023/01

 被引用回数:0 パーセンタイル:0.02(Physics, Multidisciplinary)

The understanding of the lattice dynamics is essential for engineering the thermal transport properties in quantum materials. Based on the canonical point of view, acoustic phonons are believed to be the principal thermal carriers in heat flow. Here, in this work, optical phonons are elucidated to play a pivotal role in determining the lattice thermal conductivity in thermoelectric material SnS by using the state-of-the-art inelastic neutron scattering technique combined with first-principles calculations. Additionally, in contrast to acoustic phonons, optical phonons are observed to exhibit pronounced softening and broadening with temperature. Our observations not only shed light on the significance of the optical phonons in thermal transport but also provide a vital clue to suppress the propagation of optical phonons to optimize the thermoelectric performance of SnS.

論文

Heat-induced structural changes in magnesium alloys AZ91 and AZ31 investigated by in situ synchrotron high-energy X-ray diffraction

Liu, X. J.*; 徐 平光; 城 鮎美*; Zhang, S. Y.*; 菖蒲 敬久; 行武 栄太郎*; 秋田 貢一*; Zolotoyabko, E.*; Liss, K.-D.*

Journal of Materials Science, 57(46), p.21446 - 21459, 2022/12

 被引用回数:0 パーセンタイル:0(Materials Science, Multidisciplinary)

In situ time/temperature-resolved synchrotron high-energy X-ray diffraction is applied to study heat-mediated structural changes and phase transformations in rolled sheets of AZ91 and AZ31 magnesium alloys. Azimuthal diffraction intensities along the Debye-Scherrer rings (AT-plots) are used to obtain information on grain recovery and recrystallization temperatures as well as temperature-assisted grain rotations. The azimuthally integrated diffraction intensities, plotted as functions of the scattering vector (QT-plots), provide vital data on the temperature-dependent lattice parameters of the Mg/Al matrix and intermetallic precipitates, as well as on the evolution of the precipitates' volume fraction. It was found that in AZ31, the main precipitates are of the AlMn type, which is rather stable in the investigated temperature range (up to 773 K). In contrast, in AZ91, the major intermetallic precipitates, Al$$_{12}$$Mg$$_{17}$$, undergo complete dissolution above 600 K. It is caused by the enhanced diffusion of Al into the Mg/Al matrix, which according to the Al-Mg phase diagram, can adopt more Al at elevated temperatures. This diffusion is revealed by the proportional diminishing of the matrix lattice parameter (chemical strain), allowing us to quantify the Al content in the matrix. Fast temperature-dependent manipulation with intermetallic content in the Mg/Al alloy can, in principle, be used for controlling its mechanical properties.

論文

First observation of the decay of the 13/2$$^+$$ isomer in $$^{183}$$Hg and $$B$$(${it M}$2) systematics of neutron transitions across the nuclear chart

Huang, H.*; Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Li, Z. H.*; Guo, C. Y.*; Barzakh, A. E.*; Van Duppen, P.*; Andel, B.*; et al.

Physics Letters B, 833, p.137345_1 - 137345_8, 2022/10

 被引用回数:0 パーセンタイル:0.02(Astronomy & Astrophysics)

The decay of the 13/2$$^+$$ isomeric state in $$^{183}$$Hg was observed for the first time following the $$alpha$$ decay of the 13/2$$^+$$ isomer in $$^{187}$$Pb produced in the $$^{142}$$Nd$$(^{50}$$Cr$$, 2p3n)$$ reaction. Using $$alpha$$-$$gamma$$ delayed coincidence measurements, the half-life of this isomer was measured to be 290(30) $$mu$$s. This isomer is proposed to deexcite by an unobserved low-energy $$M$$2 transition to the known 9/2$$^-$$ member of a strongly prolate-deformed 7/2$$^-$$[514] band, followed by a 105-keV $$M$$1 transition to the bandhead. A lower limit of B($$M$$2)$$geq$$0.018 W.u. was deduced for the unobserved transition. The presumed retardation is proposed to be due to the notable shape change between the initial, nearly spherical, and the final, strongly deformed, states. A similar scenario is also considered for the 13/2$$^+$$ isomer in $$^{181}$$Hg, suggesting both are cases of shape isomers. The B($$M$$2) systematics of neutron transitions across the nuclear chart is discussed.

論文

Novel graphene-based foam composite as a highly reactive filter medium for the efficient removal of gemfibrozil from (waste)water

Khalil, A. M. E.*; Han, L.*; Maamoun, I.; Tabish, T. A.*; Chen, Y.*; Eljamal, O.*; Zhang, S.*; Butler, D.*; Memon, F. A.*

Advanced Sustainable Systems (Internet), 6(8), p.2200016_1 - 2200016_16, 2022/08

 被引用回数:0 パーセンタイル:0(Green & Sustainable Science & Technology)

Graphene-based materials have emerged as alternative adsorbents, but their success in removing pharmaceutical contaminants has been limited due to degradation caused by restacking and limited control over their sizes and porosities. Driven by this issue, in the current study, to counteract the restacking behavior, graphene sheets are supported on a thread/rod-like matrix structure in a boron nitride foam material, and a novel porous composite foam-supported graphene is synthesized. The as-prepared novel composite offers extraordinary features, such as high absorption kinetics, large available surface area, high porosity, ecofriendliness and cost-effective synthesis, and excellent affinity to emerging pharmaceutical contaminants. When batch-testing graphene-based foam material and porous graphene nanosheets to remove gemfibrozil (GEM) from wastewater samples, rapid adsorption kinetics (less than 5 min) are exhibited by the graphene-based foam. Column filter studies are conducted for both materials to test their performance in removing GEM from distilled water, synthetic graywater, and actual wastewater. Overall, the foam composite-based filter marginally outperforms the sand-supported graphene filter and significantly outperforms the unsupported graphene filter. A numerical MATLAB model is developed to simulate the reactive solute transport of GEM influent through the foam filter. Also, a formal sensitivity analysis is conducted to identify the key parameters influencing the model results.

論文

Fine structure in the $$alpha$$ decay of the 8$$^{+}$$ isomer in $$^{216,218}$$U

Zhang, M. M.*; Tian, Y. L.*; Wang, Y. S.*; Zhang, Z. Y.*; Gan, Z. G.*; Yang, H. B.*; Huang, M. H.*; Ma, L.*; Yang, C. L.*; Wang, J. G.*; et al.

Physical Review C, 106(2), p.024305_1 - 024305_6, 2022/08

 被引用回数:1 パーセンタイル:56.18(Physics, Nuclear)

The extremely neutron-deficient even-even uranium isotopes $$^{216,218}$$U were produced in the complete-fusion reactions induced by impinging $$^{40}$$Ar and $$^{40}$$Ca ions on $$^{180,182,184}$$W targets. Fusion evaporation residues were separated in flight by the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure) and subsequently identified using the recoil-$$alpha$$-correlation method. In this paper, we report on new $$alpha$$-decay activities with $$E_{alpha} = 10163(27)$$ keV for $$^{216}$$U and $$E_{alpha} = 10073(16)$$ keV for $$^{218}$$U, which decay from the 8$$^{+}$$ isomeric states of $$^{216,218}$$U into the 2$$^{+}$$ states of their daughter nuclei $$^{212,214}$$Th, respectively. The new results extend the systematics of the $$alpha$$-decay fine structure for the $$N$$ = 124 and 126 even-even isotones.

論文

Transport model comparison studies of intermediate-energy heavy-ion collisions

Walter, H.*; Colonna, M.*; Cozma, D.*; Danielewicz, P.*; Ko, C. M.*; Kumar, R.*; 小野 章*; Tsang, M. Y. B*; Xu, J.*; Zhang, Y.-X.*; et al.

Progress in Particle and Nuclear Physics, 125, p.103962_1 - 103962_90, 2022/07

 被引用回数:23 パーセンタイル:96.81(Physics, Nuclear)

原子核-原子核衝突や原子核の状態方程式の研究において、反応計算モデルは重要なツールとなり、世界中で開発が進んでいる。本論文は、原子力機構のJQMD-2.0を含め、現在開発中の複数のコード開発者の協力により、これらコードを同じ条件で比較することで共通点や差異を明らかにしたプロジェクトTransport Model Evaluation Project (TMEP)を総括したものである。参加したコードはBoltzmann-Uehling-Uhlenbeck(BUU)法に基づく13のコードと、Quantum Molecular Dynamics (QMD)法に基づく12のコードであった。プロジェクトでは、Au原子核同士を衝突させてその終状態を観測する現実的な計算や、一辺が640nmの箱に核子を詰めて時間発展させる仮想的な計算を行った。その結果、BUU法コードとQMD法コードは計算原理が異なるため、計算の設定に関係なく系統的な差異が生じることが明らかになった。その一方で、同じ方法を採用するコード間の比較では、時間発展を細かく計算することでコード間の差は埋まっていき、一定の収束値を持つことが示された。この結果は今後開発される同分野のコードのベンチマークデータとして有用なものであるだけでなく、原子核基礎物理学の実験や理論研究の標準的な指針としても役に立つことが期待される。

論文

First observation of a shape isomer and a low-lying strongly-coupled prolate band in neutron-deficient semi-magic $$^{187}$$Pb

Zhang, W. Q.*; Andreyev, A. N.; Liu, Z.*; Seweryniak, D.*; Huang, H.*; Li, Z. H.*; Li, J. G.*; Guo, C. Y.*; 他34名*

Physics Letters B, 829, p.137129_1 - 137129_7, 2022/06

 被引用回数:3 パーセンタイル:87.48(Astronomy & Astrophysics)

Prompt and delayed $$gamma$$-ray spectroscopy of the neutron-deficient, semi-magic isotope $$^{187}$$Pb has been performed at the Argonne Gas-Filled Analyzer. A new 5.15(15)-$$mu$$s isomeric state at only 308 keV above the spherical 3/2$$^{-}$$ ground state is identified and classified as a shape isomer. A strongly-coupled band is observed on top of the isomer, which is nearly identical to the one built on the prolate 7/2$$^{-}$$[514] Nilsson state in the isotone $$^{185}$$Hg. Based on this similarity and on the result of the potential-energy surface calculations, the new isomer in $$^{187}$$Pb is proposed to originate from the same configuration. The retarded character of the 308-keV transition can be well explained by the significant difference between the prolate parent and spherical daughter configurations, leading to the shape isomerism. The combined results of the present work and the previous $$alpha$$-decay and laser spectroscopy studies present evidence for triple shape coexistence at low energy in the negative-parity configurations of $$^{187}$$Pb, which is well reproduced by the potential-energy surface calculations.

論文

Status of the uncertainty quantification for severe accident sequences of different NPP-designs in the frame of the H-2020 project MUSA

Brumm, S.*; Gabrielli, F.*; Sanchez-Espinoza, V.*; Groudev, P.*; Ou, P.*; Zhang, W.*; Malkhasyan, A.*; Bocanegra, R.*; Herranz, L. E.*; Berda$"i$, M.*; et al.

Proceedings of 10th European Review Meeting on Severe Accident Research (ERMSAR 2022) (Internet), 13 Pages, 2022/05

The current HORIZON-2020 project on "Management and Uncertainties of Severe Accidents (MUSA)" aims at applying Uncertainty Quantification (UQ) in the modeling of Severe Accidents (SA), particularly in predicting the radiological source term of mitigated and unmitigated accident scenarios. Within its application part, the project is devoted to the uncertainty quantification of different severe accident codes when predicting the radiological source term of selected severe accident sequences of different nuclear power plant designs, e.g. PWR, VVER, and BWR. Key steps for this investigation are, (a) the selection of severe accident sequences for each reactor design, (b) the development of a reference input model for the specific design and SA-code, (c) the selection of a list of uncertain model parameters to be investigated, (d) the choice of an UQ-tool e.g. DAKOTA, SUSA, URANIE, etc., (e) the definition of the figures of merit for the UA-analysis, (f) the performance of the simulations with the SA-codes, and, (g) the statistical evaluation of the results using the capabilities, i.e. methods and tools offered by the UQ-tools. This paper describes the project status of the UQ of different SA codes for the selected SA sequences, and the technical challenges and lessons learnt from the preparatory and exploratory investigations performed.

論文

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

 被引用回数:39 パーセンタイル:99.78(Materials Science, Multidisciplinary)

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.

論文

Structure of an aqueous RbCl solution in the gigapascal pressure range by neutron diffraction combined with empirical potential structure refinement modeling

Zhang, W. Q.*; 山口 敏男*; Fang, C. H.*; 吉田 亨次*; Zhou, Y. Q.*; Zhu, F. Y.*; 町田 真一*; 服部 高典; Li, W.*

Journal of Molecular Liquids, 348, p.118080_1 - 118080_11, 2022/02

 被引用回数:1 パーセンタイル:45.59(Chemistry, Physical)

3mol/kgのRbCl水溶液におけるイオンの水和・会合と水素結合した水の構造を、298K/0.1MPa, 298K/1GPa, 523K/1GPa, 523K/4GPaにおける中性子回折と経験的ポテンシャル構造精密化モデリングにより調べた。その結果、構造パラメータは温度と圧力に依存していることがわかった。高圧・高温条件では、Rb$$^+$$とCl$$^-$$の第二水和層がより明確になる。第一水和層におけるRb$$^+$$の平均酸素配位数は、配位距離を0.290nmから0.288nmに縮めながら、常圧では6.3だったのが、4GPaでは8.9に増加した。第一水和シェルのCl$$^-$$の平均酸素配位数は、常圧で5.9、4GPaで9.1と圧力により増加し、対応する配位距離は0.322nmから0.314nmへと減少した。Rb$$^+$$と中心の水分子の第一溶媒和シェルにおける水双極子の配向は圧力に敏感であるが、Cl$$^-$$の第一溶媒和シェルにおける水双極子の配向は温度圧力によらずあまり変化しなかった。Rb$$^+$$-Cl$$^-$$の隣接イオンペアの数は、温度が高くなると減少し、圧力が高くなると増加する。水分子は密に詰まっており、極限状態では水分子の四面体水素結合ネットワークはもはや存在しない。

論文

Modelling and simulation of the source term for a sodium cooled fast reactor under hypothetical severe accident conditions; Final report of a coordinated research project

Arokiaswamy, J. A.*; Batra, C.*; Chang, J. E.*; Garcia, M.*; Herranz, L. E.*; Klimonov, I. A.*; Kriventsev, V.*; Li, S.*; Liegeard, C.*; Mahanes, J.*; et al.

IAEA-TECDOC-2006, 380 Pages, 2022/00

IAEAの共同研究プロジェクト「シビアアクシデント条件下におけるプロトタイプナトリウム冷却高速炉からの放射性物質の放出」は、シビアアクシデント条件下における、リファレンスとなるナトリウム冷却高速炉の施設内における放射性物質および燃料粒子の存在量の、異なる時間スケールにおける現実的な数値シミュレーションを目的として実施された。解析のスコープは3つに分割され、3つのワークパッケージ(WP)として定義された:(1)炉内ソースターム評価、(2)一次系/格納容器系境界のソースターム評価、および(3)格納容器内の現象分析。WP-1の参加機関の結果を比較すると、希ガスおよび放射性セシウムの放出割合、およびカバーガスへの放射性核種の放出割合はよく一致した。共通の圧力履歴を用いたWP-2の解析では、各機関の解析結果はよく一致し、いずれの機関の解析手法も同程度の精度を有することが示された。先行するWPにおける解析と分離するため、放出割合をあらかじめ設定したスタンドアロンケースがWP-3にて定義された。WP-3の全参加機関によるスタンドアロンケースの解析結果は全般的に一致した。

論文

A Novel method to uniquely determine the parameters in Gurson-Tvergaard-Needleman model

Zhang, T.; Lu, K.; 真野 晃宏; 山口 義仁; 勝山 仁哉; Li, Y.

Fatigue & Fracture of Engineering Materials & Structures, 44(12), p.3399 - 3415, 2021/12

 被引用回数:6 パーセンタイル:69.66(Engineering, Mechanical)

GTNモデルは、延性金属の微細組織の力学挙動を考慮するモデルであるとともに、式が明確な物理的意味を表すことから、延性金属の破壊予測のためのアプローチとして期待されている。一方、強い相関のある8つのモデルパラメータの決定が困難なため、工学的な応用はほとんど進んでいない。本研究では、GTNモデルの物理的背景に基づいて、GTNモデルのパラメータを決定するための一連の手法を提案した。具体的には、連続体損傷力学の考え方を活用し、一軸引張試験における有効ヤング率の変化からボイドの体積分率の増加を実験的に求めることで、ボイドの生成に関する3つのパラメータの値を決定した。その他のGTNモデルのパラメータに関しては、化学組成分析、ボイドが含まれる単位セルモデルを用いた解析及び有限要素逆解析により一意に決定した。また、これらのパラメータ決定手法の妥当性を、炭素鋼STPT410の亀裂付き試験片と亀裂のない試験片の両方の破壊試験の結果と決定したパラメータを用いた数値解析結果との比較を通じて確認した。

論文

Crystalline fully carboxylated polyacetylene obtained under high pressure as a Li-ion battery anode material

Wang, X.*; Tang, X.*; Zhang, P.*; Wang, Y.*; Gao, D.*; Liu, J.*; Hui, K.*; Wang, Y.*; Dong, X.*; 服部 高典; et al.

Journal of Physical Chemistry Letters (Internet), 12(50), p.12055 - 12061, 2021/12

 被引用回数:4 パーセンタイル:42.16(Chemistry, Physical)

置換ポリアセチレンは、ポリアセチレン骨格の化学的安定性,物性,付加機能の向上が期待されるが、その多様性は非常に限られている。今回我々は、固体のアセチレンジカルボン酸に外圧を加えることにより、従来の方法では合成が非常に困難であったトランス-ポリアセチレン骨格上のすべての炭素がカルボキシル基に結合した結晶性のポリ-ジカルボキシルアセチレンができることを報告する。重合は、水素結合を利用したトポケミカル反応であった。このユニークな構造は、カルボニル基の極めて高い含有量とポリアセチレン骨格の高い導電性を組み合わせたもので、リチウムイオン電池(LIB)負極として高い比容量と優れたサイクル/レート性能を示す。我々は、完全に機能化された結晶性ポリアセチレンを紹介し、高分子LIB材料や活性基を多く含む高分子材料合成のために圧力重合が有力な方法であることを提案する。

論文

Long decay length of magnon-polarons in BiFeO$$_{3}$$/La$$_{0.67}$$Sr$$_{0.33}$$MnO$$_{3}$$ heterostructures

Zhang, J.*; Chen, M.*; Chen, J.*; 山本 慧; Wang, H.*; Hamdi, M.*; Sun, Y.*; Wagner, K.*; He, W.*; Zhang, Y.*; et al.

Nature Communications (Internet), 12, p.7258_1 - 7258_8, 2021/12

 被引用回数:8 パーセンタイル:72.26(Multidisciplinary Sciences)

Magnons can transfer information in metals and insulators without Joule heating, and therefore are promising for low-power computation. The on-chip magnonics however suffers from high losses due to limited magnon decay length. In metallic thin films, it is typically on the tens of micrometre length scale. Here, we demonstrate an ultra-long magnon decay length of up to one millimetre in multiferroic/ferromagnetic BiFeO$$_{3}$$(BFO)/La$$_{0.67}$$Sr$$_{0.33}$$MnO$$_{3}$$ (LSMO) heterostructures at room temperature. This decay length is attributed to a magnon-phonon hybridization and is more than two orders of magnitude longer than that of bare metallic LSMO. The long-distance modes have high group velocities of 2.5 km$$^{-1}$$ as detected by time-resolved Brillouin light scattering. Numerical simulations suggest that magnetoelastic coupling via the BFO/LSMO interface hybridizes phonons in BFO with magnons in LSMO. Our results provide a solution to the long-standing issue on magnon decay lengths in metallic magnets and advance the bourgeoning field of hybrid magnonics.

154 件中 1件目~20件目を表示