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Determining impact parameters of heavy-ion collisions at low-intermediate incident energies using deep learning with convolutional neural networks

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Physical Review C 2022年第3期105卷 034611-034611页

作者： X. Zhang (张鑫) X. Liu (刘星泉) Y. Huang (黄宇) W. Lin (林炜平) H. Zheng (郑华) R. Wada A. Bonasera Z. Chen (陈志强) L. Chen (陈蕾) J. Han (韩纪锋) R. Han (韩瑞) M. Huang (黄美容) Q. Hu (胡强) Q. Leng (冷强钟) C. W. Ma (马春旺) G. Qu (曲国峰) P. Ren (任培培) G. Tian (田国玉) Z. Xu (徐子虚) Z. Yang (杨振雷) L. Zhang (张丽娜) Key Laboratory of Radiation Physics and Technology of the Ministry of Education Sichuan University Chengdu 610064 China School of Physics and Information Technology Shaanxi Normal University Xi'an 710119 China Cyclotron Institute Texas A&M University College Station Texas 77843 USA Laboratori Nazionali del Sud INFN via Santa Sofia 62 95123 Catania Italy Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China College of Physics and Electronics information Inner Mongolia University for Nationalities Tongliao 028000 China School of Physics Henan Normal University Xinxiang 453007 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu 610213 China School of Information Sciences and Engineering Lanzhou University Lanzhou 730000 China

A deep learning based method with the convolutional neural network (CNN) algorithm for determining the impact parameters is developed by using constrained molecular-dynamics model simulations, focusing on the heavy-ion collisions at the low-intermediate incident energies from several tens to one hundred MeV/nucleon in which the emissions of heavy fragments with the charge numbers larger than three become crucial. To make the CNN applicable in the task of the impact-parameter determination at the present energy range, specific improvements are made in the input selection, the CNN construction, and the CNN training. It is demonstrated from the comparisons of the deep CNN method and the conventional methods with the impact-parameter-sensitive observables that the deep CNN method shows better performance for determining the impact parameters, especially leading to the capability of providing better recognition of the central collision events. With a proper consideration of the experimental filter effect in both training and testing processes to keep consistency with the actual experiments, the good performance of the deep CNN method holds and performs significantly better in terms of predicting the impact parameters and recognizing the central collision events compared with conventional methods, demonstrating the superiority of the present deep CNN method. The deep CNN method with the consideration of the filter effect is applied in the deduction of nuclear stopping power. Higher accuracy for the stopping power deduction is achieved benefitting from the better impact-parameter determination using the deep CNN method, compared with using conventional methods. This result reveals the importance of selecting a reliable impact-parameter-determination method in the experimental deduction of the nuclear stopping power as well as other observables.

关键词： Low & intermediate energy heavy-ion reactions Convolutional neural networks Machine learning Nuclear data analysis & compilation

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Limit load estimation for finite plates with semi-elliptical defects under tensile loading

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Journal of Physics: Conference Series 2021年第1期1777卷

作者： K K Shi X L Fu H Xie X J Shao J Tian Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan China

The ASME code allows the designer to circumvent many of the problems arising in design by elastic analysis by performing plastic or limit analysis of the component. Unlike elastic analysis, these analyses take account of the redistribution of stress upon yield. In limit analysis, the calculation of the limit load for finite plate with different semi-elliptical defects is an important stage for mechanical safety evaluation. The elastic compensation technique proposed by Mackenzie can be used to provide the limit load of a structure with a finite element method and aims at producing a suitable stress filed for the lower bound theory. In the present study, it is assumed that the finite plate exists three kinds of semi-elliptical cracks with low aspect ratio a/c (a/c=0.1, 0.5 and 1.0), respectively. The improved elastic compensation technique realized by finite element method is applied in the limit load estimation. At last, the results show that the improved elastic compensation technique can be used to obtain the limit value for the finite plate with different semi-elliptical defects under tensile loading. Moreover, the improved elastic compensation technique can be easily implemented in any finite element method and enables the limit load for any complex structure to be obtained swiftly.

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Comparisons of Subgrid-Scale Models for OpenFoam Large- Eddy Simulation

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Journal of Physics: Conference Series 2021年第4期1802卷

作者： Zhipeng Feng Huanhuan Qi Xuan Huang Shuai Liu Jian Liu Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu Sichuan China

OpenFOAM is a free, open-source software package that can be used for the solutions of computational fluid dynamics and simulation of various fluid flow processes. Nevertheless, OpenFOAM still lacks default settings and a large number of different numerical schemes and turbulent models should be validated. In this paper, the unsteady flow around a cylinder (Re=3900) is calculated by the large eddy simulation of OpenFOAM. The predictions include the drag and lift coefficient, the pressure distribution around the cylinder, the velocity distribution and Reynolds stress distribution in the wake region, as well as the prediction of the recirculation length and separation angle. Thanks to several simulations, these five subgrid-scale (SGS) models are compared and studied: The Smagorinsky SGS model, wall adaptive local eddy visibility SGS model, dynamic SGS model with Lagrangian averaging, dynamic one equation eddy visibility model, one equation eddy visibility model. The numerical results are verified with the published experimental data.

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Study on irradiation hardening of RPV steel based on modified crystal plastic finite element model

Study on irradiation hardening of RPV steel based on modifie...

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2019 Transactions of the American Nuclear Society, ANS 2019

作者： Wang, Xiaotong Yao, Weihua Luo, Ying Dong, Yuanyuan Science and Technology on Reactor System Design Technology Lab Nuclear Power Institute of China Chengdu China Nuclear Power Institute of China Chengdu China

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Emergent grain boundary phases in stressed polycrystalline thin films

arXiv

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arXiv 2022年

作者： Wang, Mengyuan Yan, Ruilin Han, Xiao Wang, Hailong Upmanyu, Moneesh CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Anhui Hefei230027 China Department of Mechanical and Industrial Engineering Northeastern University BostonMA02115 United States

The grain boundary (GB) microstructure influences and is influenced by the development of residual stresses during synthesis of polycrystalline thin films. Recent studies have shown that the frustration between the preferred growth direction and rotations of abutting crystals to local cusps in GB energies leads to internal stresses localized within nanoscopic surface layers around the valleys and ridges that form at emergent boundaries (eGBs). Using a combination of continuum frameworks, numerical analyses and all-atom simulations of bicrystal h111i copper films, we show that eGBs tune their surface morphology and rotation extent in response to external strains. Compression favors rotation to and growth of low energy GB phases (complexions) at eGB valleys while tension favors the transitions at eGB ridges, a reflection of the stress-induced mass efflux/influx that changes the energetic balance between interfacial and deformation energies. Molecular dynamics simulations of strained and growing bicrystal films reveal that the eGB phase transition is coupled to island formation at the surface triple junctions, providing a direct link between eGB phases and surface step flow. The interplay between eGB structure, morphology and mechanics emerges as a crucial ingredient for predictive understanding of stress and morphological evolution during film growth, with broad implications for multifunctional response of polycrystalline surfaces in a diverse range of surface phenomena such as surface mediated deformation, interfacial embrittlement, thermal grooving, stress corrosion, surface catalysis and topological conduction. © 2022, CC BY.

关键词： Residual stresses

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Numerical simulation and experimental research of shear-driven water film on flat plate

Numerical simulation and experimental research of shear-driv...

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CSAA/IET International Conference on Aircraft Utility systems (AUS 2024)

作者： Qinyang Li Ning Guan Bo Ning Guangya Zhu Dalin Zhang Weijian Chen Key Laboratory of Aircraft Environment Control and Life Support MIIT Nanjing University of Aeronautics and Astronautics Nanjing People's Republic of China College of Aeronautics Shandong Jiaotong University No.5001 Haitang Road Changqing University Science and Technology Park Jinan People's Republic of China Utility System Design and Research Department Jiangxi Hongdu Aviation Industry Group Company Ltd. Nanchang People's Republic of China

ISBN: (数字)9781837242108

The supercooled water droplets in the air will form a water film on the aircraft during flight, which will then form icing, which will have an impact on the aerodynamic performance of the aircraft and even endanger the flight safety. In this paper, based on the Eulerian Wall Films model, the partial wetting effect is introduced, and the water film flow on flat plates driven by airflow shear force is investigated. The flow behaviours of water film with different contact angles under different flow rates were explored through water film test. The effectiveness of the calculation method for water film flow characteristics in this paper was verified by comparison between numerical simulation and test records, which laid a foundation for the anti-icing calculation in subsequent studies.

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Biomechanical Finite Element Methods Study of a Novel Internal Fixation system for Lumbar Spondylolysis

SSRN

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SSRN 2025年

作者： Li, Jingyuan Du, Chengfei Wang, Yulei Du, Di Liang, Jinlong Shao, Nengqi Feng, Fanzhe Xu, Wenhao Xu, Yongqing Cui, Yi Center for Joint Surgery Intelligent Manufacturing and Rehabilitation Engineering Center The First Affiliated Hospital of Army Medical University Chongqing400038 China Chongqing Municipal Science and Technology Bureau Key Laboratory of Precision Medicine in Joint Surgery Chongqing400038 China Chongqing Municipal Education Commission Key Laboratory of Joint Biology Chongqing400038 China Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of mechanical engineering Tianjin University of Technology Tianjin300384 China Department of Orthopaedic Surgery 920th Hospital of Joint Logistics Support Force Kunming650032 China Department of Orthopaedic Surgery 920th Hospital of Joint Logistics Support Force No. 212 of Da-Guan Road Xishan District Kunming650032 China

ObjectiveThis study aimed to verify the biomechanical efficacy of a novel internal fixation system for repairing lumbar spondylolysis (LS). Additionally, the changes in the mechanical performance of the novel internal fixation device during compression were *** healthy 25-year-old male volunteer was recruited for lumbar spine CT data acquisition to construct and validate a nonlinear finite element model of the L4-S1 spinal segment (A). Based on this, models were established for L5 spondylolysis (B), traditional internal fixation (C), and the pressurization process of the novel LS repair device fixation (D→E→F). For these six models, we constrained the lower surface of the S1 vertebral body while applying an axial compression force of 500 N and a moment load of 7.5 N·m on the upper surface of the L4 vertebral body to simulate six motions of the lumbar spine. The performance of each finite element model was evaluated by comparing the range of motion (ROM), maximum displacement, and maximum pressure experienced by the lumbar spine under different motion *** with Model C, Models D, E, and F exhibited a reduced ROM and maximum displacement (1%-38.5%, 12.8%-63.6%, and 32.8%-80.2%) compared with Model C during six different motions. Notably, compared with Model C, the novel internal fixation models consistently demonstrated a decreasing trend in the maximum stress on the intervertebral discs (IVD) and an increasing trend in the maximum stress on the articular cartilage and maximum stress and displacement of the bone graft. Moreover, the novel internal fixation model displayed larger ranges of evenly distributed stresses on the isthmus and reduced maximum stress on the internal fixation device across all six motions, with improved stiffness effects during the pressurization process of the novel internal fixation system (D→E→F).ConclusionsAccording to several mechanical comparisons, the novel internal fixation system had better biomechan

关键词： Axial compression

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Bayesian Optimization Framework for Efficient Fleet design in Autonomous Multi-Robot Exploration

arXiv

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arXiv 2024年

作者： Concha, David Molina Li, Jiping Yin, Haoran Park, Kyeonghyeon Lee, Hyun-Rok Lee, Taesik Sirohi, Dhruv Lee, Chi-Guhn The Dynamic Optimization and Reinforcement Learning Laboratory The Department of Mechanical & Industrial Engineering University of Toronto TorontoONM5S3G8 Canada The Department of Electrical & Computer Engineering University of Toronto TorontoONM5S3G8 Canada The Division of Engineering Science The Faculty of Applied Science and Engineering University of Toronto TorontoONM5S3G8 Canada The Complex System Design Laboratory The Department of Industrial and Systems Engineering Korea Advanced Institute of Science and Technology Daejeon34141 Korea Republic of The Department of Industrial Engineering Inha University Incheon22212 Korea Republic of

This study addresses the challenge of fleet design optimization in the context of heterogeneous multi-robot fleets, aiming to obtain feasible designs that balance performance and costs. In the domain of autonomous multi-robot exploration, reinforcement learning agents play a central role, offering adaptability to complex terrains and facilitating collaboration among robots. However, modifying the fleet composition results in changes in the learned behavior, and training multi-robot systems using multi-agent reinforcement learning is expensive. Therefore, an exhaustive evaluation of each potential fleet design is infeasible. To tackle these hurdles, we introduce Bayesian Optimization for Fleet design (BOFD), a framework leveraging multiobjective Bayesian Optimization to explore fleets on the Pareto front of performance and cost while accounting for uncertainty in the design space. Moreover, we establish a sub-linear bound for cumulative regret, supporting BOFD’s robustness and efficacy. Extensive benchmark experiments in synthetic and simulated environments demonstrate the superiority of our framework over state-of-the-art methods, achieving efficient fleet designs with minimal fleet evaluations. Copyright © 2024, The Authors. All rights reserved.

关键词： Multipurpose robots

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Beyond biochemical patterning: How mechanical bistability governs robust organoid morphogenesis

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Mechanobiology in Medicine 2025年第2期3卷

作者： Qigan Gao Yuehua Yang Haoxiang Yang Hongyuan Jiang CAS Key Laboratory of Mechanical Behavior and Design of Materials CAS Center for Excellence in Complex System Mechanics Department of Modern Mechanics University of Science and Technology of China Hefei Anhui 230026 China

Understanding the regulatory mechanisms of intestinal organoid morphogenesis remains a fundamental challenge in organoid biology. Emerging evidence highlights mechanical bistability as a critical regulator, mediated by dynamic lumen-actomyosin feedback. The recently developed 3D vertex model demonstrates that crypt curvature modulates actomyosin localization via mechanosensitive pathways, creating two stable morphological states—bulged or budded—depending on mechanical history. This model advances beyond static vertex models by incorporating epithelial thickness variations and lumen pressure effects, explaining previously unresolved phenomena like irreversible crypt budding and snap-through transitions. The findings establish a new framework for understanding mechanical decision-making in epithelial tissues, with implications for organoid engineering and developmental biology.

关键词： Mechanical bistability Intestinal organoids Vertex model Morphogenesis Epithelial mechanics

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Evaluation of surface wind speed over East Asia and the adjacent ocean in three reanalyses using satellite and in-situ observations

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Atmospheric and Oceanic science Letters 2025年

作者： Li, Siyuan Wang, Kai Miao, Hao Zhu, Xuedan Liu, Yanjie Li, Jinxiao Wang, Wei Zheng, Xiao Feng, Juan Wang, Xiaocong Shanghai Investigation Design and Research Institute Co. Ltd. Shanghai China College of Atmospheric Science Nanjing University of Information Science and Technology Nanjing China China Meteorological Administration Transportation Meteorology Key Laboratory Nanjing Joint Institute for Atmospheric Sciences Nanjing China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Center for Monsoon System Research Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

Surface wind speed (SWS) not only plays a crucial role in regulating the Earth's energy and hydrological cycle, but also is an important source of sustainable renewable energy. This study assesses the credibility of SWSs in three reanalyses (ERA5, MERRA2, and JRA-55) in East Asia using both satellite and in-situ observations. Results show all three reanalyses can capture the spatial pattern of SWS as in observations, yet there are notable differences in magnitude. On land, ERA5 and MERRA2 overestimate the SWS by about 0.6 and 1.5 m s⁻¹, respectively, whereas JRA-55 underestimates it. The biases over the oceans are opposite to those on land and are relatively small due to the assimilation of observations of oceanic surface winds. Overall, JRA-55 and ERA5 offer better estimates of seasonal means and variances of SWS than MERRA2. The observed SWS shows a negative trend of −0.08 m s⁻¹/10 yr on land and a positive trend of 0.09 m s⁻¹/10 yr in the western North Pacific. Only JRA-55 shows similar trends to observations over both land and ocean, while ERA5 and MERRA2 show varying degrees of deviation from the observations. Further investigation shows that there is a strong link between the trend of SWS and that of the large-scale circulation, and that a large part of the SWS trend can be attributed to changes in large-scale circulations. 摘要利用卫星和地面站点观测数据, 本文对再分析产品中的地表风速 (SWS) 进行了可信度评估. 研究结果表明, 再分析产品能够较好地再现SWS的观测分布特征, 但在风速的量级上则存在显著差异. 具体而言, 在陆地区域, ERA5和MERRA2分别高估了约0.6 m s⁻¹和1.5 m s⁻¹, 而JRA-55则存在低估现象;而在海洋区域, 偏差情况与陆地相反. 总体来看, JRA-55和ERA5在模拟SWS的气候态及其变率方面, 更加接近观测数据. 其中, JRA-55中SWS的年代际趋势与观测数据最为一致. © 2024

关键词： ASCAT East Asia Reanalysis Surface wind speed Trend analysis

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