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Effect of Temperature and Grain Boundary on Void Evolution in Irradiated Copper:A Phase-Field Study

Acta Metallurgica Sinica(English Letters) 2024年第9期37卷 1621-1632页

作者： Qionghuan Zeng Yiming Chen Zhongsheng Yang Yunhao Huang Zhijun Wang Junjie Li Jincheng Wang tate Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Science and Technology On Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu610213China

The continued existence of high-energy radiation in nuclear reactors at high temperatures results in the formation of radiation-induced voids,which will further lead to inevitable swellings of polycrystalline structural components and thus premature failures.A deep understanding of the effect of temperature and grain boundary on void evolution in irradiated copper is significant for preventing this kind of ***,the phase-field method was employed to study void evolution in irradiated copper under different temperatures and grain *** results show that,due to the different sensitivities of point defect production rate and vacancy diffusion rate to temperature changes,both the nucleation-growth rate and the coarsening rate during void evolution increase first and then decrease with increasing temperature;moreover,the nucleation mechanism exhibits site-saturated nucleation at low temperatures while continuous nucleation at high *** presence of grain boundary can accelerate the emergence of void because grain boundaries can absorb more interstitials than *** finer the grain size,the stronger inhibitory effect of grain boundaries on the growth rate of void,due to the formation of void denuded zone near grain *** high temperatures,the growth rate of void in fine grains is significantly reduced due to the increase of vacancy diffusion rate and the enhancement of sink effect of grain boundary on vacancy.

关键词： Void evolution Phase-field method Temperature Grain boundary

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A perspective on describing nucleonic flow and pionic observables within the ultra-relativistic quantum molecular dynamics model

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nuclear science and Techniques 2025年第3期36卷 105-118页

作者： Yang-Yang Liu Jun-Ping Yang Yong-Jia Wang Qing-Feng Li Zhu-Xia Li Cheng-Jun Xia Ying-Xun Zhang China Nuclear Data Center China Institute of Atomic EnergyBeijing 102413China School of Science Huzhou UniversityHuzhou 313000China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Center for Gravitation and Cosmology College of Physical Science and TechnologyYangzhou UniversityYangzhou 225009China Guangxi Key Laboratory of Nuclear Physics and Technology Guangxi Normal UniversityGuilin 541004China

In this work,we study the impacts of the isospin-independent momentum-dependent interaction(MDI)and near-threshold NN→NΔcross sections(σ_(NN→NΔ))on the nucleonic flow and pion production observables in the ultra-relativistic quantum molecular dynamics(UrQMD)*** the updated isospin-independent MDI and the near-threshold NN→NΔcross sections in the Ur QMD model,17 observables,which are the directed flow(v_(1))and elliptic flow(v_(2))of neutrons,protons,Hydrogen(H),and charged particles as a function of transverse momentum(p_t∕A)or normalized rapidity(y^(lab)_0),and the observables constructed from them,the charged pion multiplicity(M(π))and its ratio(M(π^(-))∕M(π^(+))),can be simultaneously described at certain forms of symmetry *** refinement of the UrQMD model provides a solid foundation for further understanding the effects of the missed physics,such as the threshold effect,the pion potential,and the momentum-dependent symmetry *** constraints on the symmetry energy at the flow characteristic density 1.2±0.6ρ_(0)and the pion characteristic density 1.5±0.5ρ_(0)were obtained with the current version of UrQMD,and the corresponding symmetry energies were S(1.2ρ_(0))=34±4 MeV and S(1.5ρ_(0))=36±8 MeV,***,the discrepancies between the data and the calculated results of v_(2)^(n)and v_(2)^(9)at high p_(t)(rapidity)imply that the roles of the missing ingredients,such as the threshold effect,the pion potential,and the momentum-dependent symmetry potential,should be investigated by differential observables,such as the momentum and rapidity distributions of the nucleonic and pionic probes over a wide beam energy range.

关键词： Momentum dependent interaction NN→NΔcross section Symmetry energy Flow andπobservable

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Correlation between the charge radii difference in mirror partner nuclei and thesymmetry energy slope

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Chinese Physics C 2024年第8期48卷 177-184页

作者： Xiao-Rong Ma Shuai Sun Rong An Li-Gang Cao School of Physics Ningxia UniversityYinchuan 750021China Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Key Laboratory of Beam Technology of Ministry of Education Institute of Radiation TechnologyBeijing Academy of Science and TechnologyBeijing 100875China

A correlation between the charge radii difference of mirror partner nucleiΔR_(ch) and the slope parameter L of symmetry energy has been built to ascertain the equation of state of isospin asymmetric nuclear *** this work,the influences of pairing correlations and isoscalar compression modulus on theΔRch are systematically investigated based on the Skyrme energy density functional *** calculated results suggest that the linear correlation betweenΔR_(ch) and L is decreased by the surface pairing *** slope parameter deduced from the difference of charge radii of mirror-pair nuclei ^(32)Ar-^(32)Si,^(36)Ca-^(36)S,^(38)Ca-^(38)Ar,and ^(54)Ni-^(54)Fe falls into the range of L=42.57−50.64 MeV,that is,the rather soft equation of state of asymmetric nuclear ***,the range of the slope parameter can also be influenced by the effective forces classified by various isoscalar incompressibility coefficients.

关键词： symmetry energy charge radius mirror-pair nuclei slope parameter

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Space Complexity of Euclidean Clustering

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IEEE Transactions on Information Theory 2025年第6期71卷 4515-4536页

作者： Zhu, Xiaoyi Tian, Yuxiang Huang, Lingxiao Huang, Zengfeng Fudan University School of Data Science Shanghai200433 China Nanjing University State Key Laboratory of Novel Software Technology New Cornerstone Science Laboratory Nanjing210023 China

The (k, z)-Clustering problem in Euclidean space Rd has been extensively studied. Given the scale of data involved, compression methods for the Euclidean (k, z)-Clustering problem, such as data compression and dimension reduction, have received significant attention in the literature. However, the space complexity of the clustering problem, specifically, the number of bits required to compress the cost function within a multiplicative error ϵ, remains unclear in existing literature. This paper initiates the study of space complexity for Euclidean (k, z)-Clustering and offers both upper and lower bounds. Our space bounds are nearly tight when k is constant, indicating that storing a coreset, a well-known data compression approach, serves as the optimal compression scheme. Furthermore, our lower bound result for (k, z)-Clustering establishes a tight space bound of Θ(nd) for terminal embedding, where n represents the dataset size. Our technical approach leverages new geometric insights for principal angles and discrepancy methods, which may hold independent interest. © 1963-2012 IEEE.

关键词： Cost functions

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Recent progress in nuclear astrophysics research and its astrophysical implications at the China Institute of Atomic Energy

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nuclear science and Techniques 2024年第12期35卷 376-408页

作者： Wei-Ping Liu Bing Guo Zhu An Bao-Qun Cui Xiao Fang Chang-Bo Fu Bin-Shui Gao Jian-Jun He Yu-Chen Jiang Chong Lv Er-Tao Li Ge-Xing Li Yun-Ju Li Zhi-Hong Li Gang Lian Wei-Ping Lin Yi-Hui Liu Wei Nan Wei-Ke Nan Yang-Ping Shen Na Song Jun Su Liang-Ting Sun Xiao-Dong Tang Luo-Huan Wang Shuo Wang You-Bao Wang Di Wu Xiao-Feng Xi Sheng-Quan Yan Li-Yong Zhang China Institute of Atomic Energy Beijing 102413China Department of Physics Southern University of Science and TechnologyShenzhen 518055China Jinping Deep Underground Frontier Science and Dark Matter Key Laboratory of Sichuan Province Liangshan 615000China School of Physics Xi’an Jiaotong UniversityXi’an 710049China Key Laboratory of Radiation Physics and Technology of the Ministry of Education Institute of Nuclear Science and TechnologySichuan UniversityChengdu 610064China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China Key Laboratory of Nuclear Physics and Ion-beam Application(MoE) Institute of Modern PhysicsFudan UniversityShanghai 200433China Joint Department for Nuclear Physics Institute of Modern PhysicsChinese Academy of Sciences and Lanzhou UniversityLanzhou 730000China CAS Key Laboratory of High Precision Nuclear Spectroscopy Institute of Modern PhysicsChinese Academy of SciencesLanzhou 73000China School of Nuclear Science and Technology University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhenChina Key Laboratory of Beam Technology and Material Modification of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China School of Mathematics and Physics Handan UniversityHandan 056005China Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China State Key Laboratory of Nuclear Physics and Technology School of PhysicsCAPTPeking UniversityBeijing 100871China

nuclear astrophysics is a rapidly developing interdisciplinary feld of research that has received extensive attention from the scientifc community since the midtwentieth ***,it uses the laws of extremely small atomic nuclei to explain the evolution of the *** to the complexity of nucleosynthesis processes and our limited understanding of nuclear physics in astrophysical environments,several critical astrophysical problems remain *** achieve a better understanding of astrophysics,it is necessary to measure the cross sections of key nuclear reactions with the precision required by astrophysical *** measurement of nuclear reaction cross sections is an important method of investigating how nuclear reactions infuence stellar *** the challenges involved in measuring the extremely low crosssections of nuclear reactions in the Gamow peak and preparing radioactive targets,indirect methods,such as the transfer reaction,coulomb dissociation,and surrogate ratio methods,have been developed over the past several *** are powerful tools in the investigation of,for example,neutron-capture(n,r)reactions with short-lived radioactive ***,direct measurement is still preferable,such as in the case of reactions involving light and stable *** an essential part of stellar evolution,these low-energy stable nuclear reactions have been of particular interest in recent *** overcome the diffculties in measurements near or deeply within the Gamow window,the combination of an underground laboratory and high-exposure accelerator/detector complex is currently the optimal ***,underground experiments have emerged as a new and promising direction of *** addition,to better simulate the stellar environment in the laboratory,research on nuclear physics under laser-driven plasma conditions has gradually become a frontier *** recent years,the CIAE team conducted a series of distinctive nuclea

关键词： nuclear astrophysics Indirect method Underground laboratory Direct measurement Lowenergy nuclear reaction

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A new liquid membrane diffusion model for characterizing the adsorption kinetics of europium by using a continuous measurement of adsorption platform

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nuclear science and Techniques 2024年第1期35卷 59-72页

作者： Hao-Qi Yu Tao Yu Jian-Hua Ye State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China CGN Cangnan Nuclear Power Co. Ltd.Cangnan 325800China Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices East China University of TechnologyNanchang 330013China School of Nuclear Science and Engineering East China University of TechnologyNanchang 330013China

To explore the kinetic adsorption under continuous and nonequilibrium states, an integration of continuous measurement and adsorption platform kinetics method was proposed, which was initially called the ICM-AP kinetics method, and a corresponding kinetic adsorption experimental method was developed. Adsorption experiments of europium(Eu) on Ca-bentonite,Na-bentonite, and the D231 cation exchange resin were performed using the ICM-AP kinetics method and continuous measurements. Because the kinetic experimental results observed in this study were different from those of traditional batch adsorption data, pseudo-first-order or pseudo-second-order kinetic models were unsuitable for fitting the experimental ***, a liquid membrane diffusion(LMD) model was developed based on the assumption of simultaneous adsorption/desorption to discuss the mechanism of kinetic adsorption. The kinetic adsorption mechanism was also studied by using *** results indicated that the proposed adsorption model can fit the experimental data more suitably, and the adsorption/desorption behaviors of Eu on bentonite and the D231 resin were simultaneously observed, suggesting that the adsorption kinetics of Eu(Ⅲ) was mainly dominated by hydrated Eu(Ⅲ) ions on the liquid membrane.

关键词： ICM-AP method LMD model Adsorption mechanism Eu(Ⅲ)

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Research progress and development tendency on storage mechanism of multi-principal element alloys for hydrogen/tritium storage

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Rare Metals 2024年第11期43卷 5549-5572页

作者： Yi-Jie Chen Jian-Wei Zhang Can-Hui Xu Mu-Hong Li Shuang-Lin Hu Yue-Xia Wang Xiao-Tao Zu Hai-Yan Xiao Xiao-Song Zhou Shu-Ming Peng Hua-Hai Shen Institute of Nuclear Physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China Key Laboratory of Nuclear Physics and Ion-Beam Application(MOE) Institute of Modern PhysicsDepartment of Nuclear Science and TechnologyFudan UniversityShanghai 200433China School of Physics University of Electronic Science and Technology of ChinaChengdu 610054China

Sustainable clean energy is gradually replacing traditional fossil energy sources in important industrial applications and is placing higher demands on the technologies of energy storage and *** development of multi-principal element alloys(MPEAs)offers a new idea for safe solid-state hydrogen storage *** to the unique characteristics of complex components and severe lattice distortion,MPEAs are predicted to have better hydrogen storage performance and more probability for modulation and enhancement,allowing them to meet the requirements of different hydrogen storage *** unique structure characteristic potentially devotes the improvement of thermodynamic and kinetic performance,such as the hydrogen storage capacity and hydrogen adsorption/desorption ***,several important modulation factors originating from components and structures facilitate the understanding of the correlation between hydrogen storage properties and ***,we highlight the correlations of hydrogen storage mechanism,with the degree of lattice distortion,the element variation or segregation and valence electron ***,the development tendency on the hydrogen storage mechanism based on the advanced microscopy and computational approach is ***,the chemically short-range ordered structure in MPEAs is predicted as a potential modification factor of the hydrogen/tritium storage properties.

关键词： Multi-principal element alloys(MPEAs) Hydrogen/Tritium storage Hydrogenation mechanism Development tendency Advanced microscopy

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3D robust anisotropic diffusion filtering algorithm for sparse view neutron computed tomography 3D image reconstruction

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nuclear science and Techniques 2024年第3期35卷 13-29页

作者： Yang Liu Teng-Fei Zhu Zhi Luo Xiao-Ping Ouyang School of Nuclear Science and Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an 710024China

The most critical part of a neutron computed tomography(NCT) system is the image processing algorithm,which directly affects the quality and speed of the reconstructed *** types of noise in the system can degrade the quality of the reconstructed ***,to improve the quality of the reconstructed images of NCT systems,efficient image processing algorithms must be *** anisotropic diffusion filtering(ADF) algorithm can not only effectively suppress the noise in the projection data,but also preserve the image edge structure information by reducing the diffusion at the image ***,we propose the application of the ADF algorithm for NCT image *** compare the performance of different algorithms in NCT systems,we reconstructed images using the ordered subset simultaneous algebraic reconstruction technique(OS-SART) algorithm with different regular terms as image processing *** the iterative reconstruction,we selected two image processing algorithms,the Total Variation and split Bregman solved total variation algorithms,for comparison with the performance of the ADF ***,the filtered back-projection algorithm was used for comparison with an iterative *** reconstructing the projection data of the numerical and clock models,we compared and analyzed the effects of each algorithm applied in the NCT *** on the reconstruction results,OS-SART-ADF outperformed the other algorithms in terms of denoising,preserving the edge structure,and suppressing *** example,when the 3D Shepp–Logan was reconstructed at 25 views,the root mean square error of OS-SART-ADF was the smallest among the four iterative algorithms,at only *** universal quality index,mean structural similarity,and correlation coefficient of the reconstructed image were the largest among all algorithms,with values of 0.9877,0.9878,and 0.9887,respectively.

关键词： NCT OS-SART Sparse-view Anisotropic diffusion filtering

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Sparse-view neutron CT 3D image reconstruction algorithm based on split Bregman method

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nuclear science and Techniques 2024年第9期35卷 41-55页

作者： Teng-Fei Zhu Yang Liu Zhi Luo Xiao-Ping Ouyang School of Nuclear Science and Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Nuclear Resources and Environment East China University of TechnologyNanchang 330013China State Key Laboratory of Intense Pulsed Radiation Simulation and Effect Xi’an 710024China

As a complement to X-ray computed tomography(CT),neutron tomography has been extensively used in nuclear engineer-ing,materials science,cultural heritage,and industrial *** of the attenuation matrix for neutron tomography with a traditional analytical algorithm requires hundreds of projection views in the range of 0°to 180°and typically takes several hours to *** a low time-resolved resolution degrades the quality of neutron *** the number of projection acquisitions is an important approach to improve the time resolution of images;however,this requires efficient reconstruction ***,sparse-view reconstruction algorithms in neutron tomography need to be *** this study,we investigated the three-dimensional reconstruction algorithm for sparse-view neu-tron CT *** enhance the reconstructed image quality of neutron CT,we propose an algorithm that uses OS-SART to reconstruct images and a split Bregman to solve for the total variation(SBTV).A comparative analysis of the performances of each reconstruction algorithm was performed using simulated and actual experimental *** to the analyzed results,OS-SART-SBTV is superior to the other algorithms in terms of denoising,suppressing artifacts,and preserving detailed structural information of images.

关键词： Neutron CT OS-SART Sparse-view 3D reconstruction Split Bregman Total variation

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A general tail item representation enhancement framework for sequential recommendation

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Frontiers of Computer science 2024年第6期18卷 137-148页

作者： Mingyue CHENG Qi LIU Wenyu ZHANG Zhiding LIU Hongke ZHAO Enhong CHEN Anhui Province Key Laboratory of Big Data Analysis and Application University of Science and Technology of China&State Key Laboratory of Cognitive IntelligenceHefei 230026China College of Management and Economics Tianjin UniversityTianjin 300072China

Recently advancements in deep learning models have significantly facilitated the development of sequential recommender systems(SRS).However,the current deep model structures are limited in their ability to learn high-quality embeddings with insufficient ***,highly skewed long-tail distribution is very common in recommender ***,in this paper,we focus on enhancing the representation of tail items to improve sequential recommendation *** empirical studies on benchmarks,we surprisingly observe that both the ranking performance and training procedure are greatly hindered by the poorly optimized tail item *** address this issue,we propose a sequential recommendation framework named TailRec that enables contextual information of tail item well-leveraged and greatly improves its corresponding *** the characteristics of the sequential recommendation task,the surrounding interaction records of each tail item are regarded as contextual information without leveraging any additional side *** approach allows for the mining of contextual information from cross-sequence behaviors to boost the performance of sequential *** a light contextual filtering component is plug-and-play for a series of SRS *** verify the effectiveness of the proposed TailRec,we conduct extensive experiments over several popular benchmark *** experimental results demonstrate that TailRec can greatly improve the recommendation results and speed up the training *** codes of our methods have been available.

关键词： sequential recommendation long-tail distribution training accelerating

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