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Evaluation of a Numerical Model for Predicting Flow and Heat Transfer in a Hexagonal Helical Cruciform Seven-Rods Bundle and Analysis of Rod Bundle Size Independence

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SSRN 2024年

作者： Jiang, Dianqiang Deng, Jian Zhang, Dalin Zhou, Xingguang Xiao, Changzhi Tian, Wenxi Qiu, Suizheng Su, Guanghui H. State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

In this study, the accuracy and applicability of the numerical model are comprehensively evaluated based on the experimental data of a hexagonal helical cruciform (HC) seven-rods bundle. The STAR CCM+ is utilized as a tool to obtain predicted results of flow and heat transfer in different flow regions. The numerical results indicate that it is an improved method to set a negative heat flux on the hexagonal wall in the laminar flow region. The Reynolds stress transport model can accurately predict the experimental results of heat transfer in the transitional flow region, with an average wall temperature deviation of 2.8℃. The SST k-ω model with cubic constitutive option can accurately predict the experimental results of the flow resistance, and a relative error of f is 1.8%. In the turbulent flow region, the SST k-ω model with cubic constitutive option provides an accurate prediction, with an average wall temperature deviation of 3.7℃. The realizable k-Ε two-layer model can accurately predict the flow resistance, and the relative error of f is 0.1%. The preferred numerical model is used to analyze the size independence of the HC rod bundle. This work provides certain guidelines for the accurate simulation in the HC seven-rods bundle. © 2024, The Authors. All rights reserved.

关键词： Computational fluid dynamics

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Research on Fine Modeling of Dispersion Fuel Plate Based on Lattice Method

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SSRN 2023年

作者： Chen, Yuqing Liu, Pengfei Li, Song Lou, Lei Li, Ang College of Nuclear Science and Technology Naval University of Engineering Wuhan China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu China

For Double Heterogeneous(DH) systems, the analysis shows that the lattice modeling method has a great advantage in efficiency compared to the stochastic explicit modeling method, but the Lattice Modeling Method with Single-Particle Universe(LMMSU) has difficulties in calculating the problem of DH system with multiple particle sizes. In this paper, a Lattice Modeling Method with Multiple -Particles Universe(LMMMU) is proposed . The LMMMU has a computational error of less than 30 pcm when dealing with particle-dispersed fuel systems and still less than 50 pcm when dealing with particle-dispersed burnable poison systems. The memory footprint is reduced to 5.21% and the computation time is reduced to 1.25% compared to the stochastic explicit modeling method. The LMMMU also shows good compatibility when dealing with the problem of filling by two types of dispersed particles. Comprehensive analysis shows that the LMMMU is better than LMMSU in terms of applicability, efficiency, and accuracy. © 2023, The Authors. All rights reserved.

关键词： Efficiency

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A Selection Method of Effective Metamorphic Relations 13

A Selection Method of Effective Metamorphic Relations

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13th International Conference on Reliability, Maintainability, and Safety, ICRMS 2022

作者： Zhang, Jie Hong, Jie Huang, Dafei Li, Meng Yan, Shiyu Gong, Helin School of Computing University of South China Hunan Hengyang China Engineering and Technology Research Center of Software Evaluation and Testing for Intellectual Hunan Hengyang China CNNC Key Laboratory on High Trusted Computing Hunan Hengyang China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu China

ISBN: (数字)9781665486903

ISBN: (纸本)9781665486903

Metamorphic testing can effectively alleviate the test oracle problem. However, the program under test needs to be executed one more time;it is particularly significant to select the metamorphic relation with the highly fault-detecting ability and improve the test cost-effectiveness. Due to the limitations of existing evaluation methods in engineering applications, a validity evaluation method for metamorphic relation is presented based on single factor and multi-factor mutation scores. It can guide their priority ranking and selection. Experiments show that this method can significantly reduce test costs. © 2022 IEEE.

关键词： Cost effectiveness

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Effect of Fission Defects on Tensile Strength of U3si2 Σ5(210) Grain Boundary from First-Principles Calculations

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SSRN 2023年

作者： Zhao, Jiajun Sun, Dan Xi, Liu Chen, Ping Zhao, Jijun Wang, Yuanyuan Dalian University of Technology Liaoning Dalian China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Sichuan Chengdu China

U3Si2 is regarded as a promising accident tolerant fuel (ATF) to replace the commercial fuel UO2;however, U3Si2 grain boundary (GB) embrittlement caused by irradiation-induced defect segregation remains to be clarified. In this work, U3Si2 Σ5(210) symmetrically tilt GB is taken as representative to elucidate the individual effect of xenon (Xe) and vacancy on the tensile strength and failure of GB using first-principles calculations. Compared with the predicted segregation energies of defects at the most energetically favourable positions of GB, Si vacancy (VSi) has much stronger preference to segregate to GB than that of Xe substitution on Si sublattice (XeSi). Moreover, the strengthening/embrittlement potency of GB with single vacancy/Xe is evaluated using the first-principles-based uniaxial tensile test. Although both VSi and XeSi yield a weakening effect on the strength of U3Si2 Σ5(210) GB, such defective GBs exhibit significantly stronger interface strengths compared to the corresponding defects segregated to UO2 Σ3(111) GB. The underlying mechanism of strength change of U3Si2 GB is discussed in terms of charge analysis. Our results can provide fundamental understanding on the mechanical behavior of irradiated GB from an atomic perspective. © 2023, The Authors. All rights reserved.

关键词： Grain boundaries

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A New Perspective of Deep Learning Testing Framework: Human-Computer Interaction Based Neural Network Testing

A New Perspective of Deep Learning Testing Framework: Human-...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Wei Kong Hu Li Qianjin Du Huayang Cao Xiaohui Kuang National Key Laboratory of Science and Technology on Information System Security Beijing China Department of Computer Science and Technology Tsinghua University Beijing China

ISBN: (数字)9798350384574

ISBN: (纸本)9798350384581

Deep learning models have revolutionized various domains but have also raised concerns regarding their security and reliability. Adversarial attacks and coverage-based testing have been extensively studied to assess and enhance the dependability of deep neural networks. However, current research in this area has reached a state of stagnation. Adversarial attacks focus on exploiting vulnerabilities in models, while coverage-based testing aims to achieve comprehensive testing but overlooks application scenarios. Moreover, evaluating test cases solely based on their fault-revealing capability is insufficient. To address these limitations, we propose an innovative interdisciplinary framework that incorporates human-computer interaction methods in deep learning security testing. By considering the attributes of model application scenarios, we can design more effective test suites that intend to reveal the model's behavior across various scenarios, aiding in the identification of potential defects. Consequently, the test suite plays a crucial role in the testing process of deep learning models, contributing to the assurance of model robustness and reliability. Additionally, we establish a comprehensive evaluation metric for test suite quality, considering factors such as diversity and naturalness. This framework promotes reliable and secure deployment of deep learning models, fostering interdisciplinary collaboration between artificial intelligence and human-computer interaction.

关键词： Deep learning Human computer interaction Measurement Diversity reception Collaboration Robustness Security

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Hard-magnetic liquid metal droplets with excellent magnetic field dependent mobility and elasticity

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Journal of Materials science & technology 2021年第33期92卷 60-68页

作者： Xiaokang He Mingyang Ni Jianpeng Wu Shouhu Xuan Xinglong Gong CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaHefei 230027China

Magnetic liquid metal droplets(MLMDs)have been proven to be very important in many fields such as flexible electronics and soft ***,soft magnetic particles such as nickel(Ni)and iron(Fe)are mixed or suspended into the liquid metal to obtain soft MLMDs(S-LMDs),which can be easily manipulated under the magnetic field due to the favorable deformability and *** addition,hard magnetic particles such as neodymium iron boron(Nd Fe B)with a high residual magnetization can also be dispersed into the liquid metal and the hard MLMDs(H-LMDs)become more compact due to the interaction between internal particles induced by *** work reports a kind of H-LMDs with high surface tension,high flexibility and mechanical robustness,whose electrical conductivity and strength are better than the *** the magnetic field,the H-LMDs have a faster response time(0.58 s)and a larger actuating velocity(4.45 cm/s)than the ***,the H-LMDs show excellent magnetic controllability,good elasticity and favorable mobility,as demonstrated by magnetically actuated locomotion,bounce tests and rolling angle ***,the droplets can be further applied in wheeldriven motors and micro-valve switches,which demonstrates their high application potential in robotic manipulation and microfluidic devices.

关键词： Magnetic liquid metal droplets NdFeB particles Magnetic controllability Micro-valve

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Study on hydrogen stratification and erosion process in Chinese SMR containment under severe accident scenario

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International Journal of Advanced Nuclear reactor design and technology 2020年 2卷 43-51页

作者： Fan, Yang Songwei, Li Wei, Zeng Zhifang, Qiu Jian, Deng Science and Technology on Reactor System Design Technology Laboratory NPIC China Design and Research Sub-institute NPIC China

During postulated severe accident, large amount of hydrogen-vapor mixture will be released into the containment and inflammable gas mixture may form. Once the gas will be ignited, the generated pressure loads can jeopardize the integrity of the internal structures. As the local accumulation of high content hydrogen related much to the stratification and erosion mechanism, it is therefore of interest whether a stratification of gas layers will form within small containment. In this study, a stratification/erosion experiment is performed and the criteria under which the steady stratification will be destroyed by steam jet discussed. Then the simulation method is validated by the experimental data. At last, several severe accident scenarios for Chinese SMR performed and one of them is adopted for containment hydrogen CFD analysis. It is shown that high content of hydrogen will form in the upper part of the containment, and clear gas stratification will form, such stratification will be enhanced due to the condensation effect of steel containment wall. © 2020

关键词： Hydrogen

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Thermochemical non-equilibrium flow characteristics of high Mach number inlet in a wide operation range

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Chinese Journal of Aeronautics 2023年第12期36卷 164-184页

作者： Chunliang DAI Bo SUN Lianjie YUE Shengbing ZHOU Changfei ZHUO Changsheng ZHOU Jianyi YU School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of High Temperature Gas Dynamics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 100049China College of Aerospace Engineering Chongqing UniversityChongqing 400044China Beijing System Design Institute of Electro-mechanic Engineering Beijing 102308China

The high-temperature non-equilibrium effect is a novel and significant issue in the flows over a high Mach number(above Mach 8)air-breathing ***,this study attempts to investigate the high-temperature non-equilibrium flows of a curved compression two-dimensional scramjet inlet at Mach 8 to 12 utilizing the two-dimensional non-equilibrium RANS ***,the thermochemical non-equilibrium gas model can predict the actual high-temperature flows,and the numerical results of the other four thermochemical gas models are only used for comparative ***,the thermochemical non-equilibrium flow fields and work performance of the inlet at Mach 8 to 12 are ***,the influences of high-temperature non-equilibrium effects on the starting characteristics of the inlet are *** results reveal that a large separation bubble caused by the cowl shock/lower wall boundary layer interaction appears upstream of the shoulder,at Mach *** separation zone size is smaller,and its location is closer to the downstream area while the thermal process changes from frozen to non-equilibrium and then to *** the increase of inflow Mach number,the thermochemical non-equilibrium effects in the whole inlet flow field gradually strengthen,so their influences on the overall work performance of the high Mach number inlet are more *** vibrational relaxation or thermal non-equilibrium effects can yield more visible influences on the inlet performance than the chemical non-equilibrium *** inlet in the thermochemical non-equilibrium flow can restart more easily than that in the thermochemical frozen *** work should provide a basis for the design and starting ability prediction of the high Mach number inlet in the wide operation range.

关键词： Non-equilibrium Scramjet inlet Starting ability Thermochemical Work performance

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Magnitude,distribution and temporal trend of nitrous oxide emissions from China's natural soils over 1980–2022

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science China Earth sciences 2025年第4期68卷 1074-1085页

作者： Songbai HONG Zimeng LI Mingsong TANG Fa LI Yitong YAO Yanzi YAN Mingzhu HE Xuhui WANG Hui ZENG Shilong PIAO School of Urban Planning and Design Shenzhen Graduate SchoolPeking UniversityShenzhen518055China Key Laboratory of Earth Surface System and Human-Earth Relations Ministry of Natural Resources of ChinaShenzhen Graduate SchoolPeking UniversityShenzhen518055China Institute of Carbon Neutrality Sino-French Institute for Earth System ScienceCollege of Urban and Environmental SciencesPeking UniversityBeijing100871China Department of Earth System Science Stanford UniversityStanfordCA94305USA Division of Geological and Planetary Sciences California Institute of TechnologyPasadenaCA91125USA Department of Soil and Environment Swedish University of Agricultural SciencesUppsala75007Sweden Joint International Research Laboratory of Catastrophe Simulation and Systemic Risk Governance Beijing Normal UniversityZhuhai519087China School of National Safety and Emergency Management Beijing Normal UniversityZhuhai519807China

Soils represent the largest contributor to global nitrous oxide(N_(2)O)***,current research efforts predominantly focus on N_(2)O emissions from agricultural soils,while studies on N_(2)O emissions from natural soils,another significant source,remain *** this study,we explored the magnitude,spatiotemporal dynamics,and drivers of N_(2)O emissions from China's natural soils over the period 1980–2022 via machine learning and a compiled novel dataset of 319 field *** results revealed that the N_(2)O flux per unit area was generally higher in the southeast compared to the northwest,and higher in forests than in *** spatial and biome heterogeneity was strongly regulated by local hydrothermal conditions and nitrogen *** averaged N_(2)O emissions over the study period were 646.2±27 Gg N_(2)O yr^(-1),with approximately equivalent contributions from forests and ***,there exhibited a significant and increasing trend from 1980 to 2022,with a rate of 2.7 Gg N_(2)O yr^(-2).Such an increase was primarily driven by the expansion of forested area and elevated nitrogen *** data-driven study presents a long-term and gridded estimate of N_(2)O emissions from China's natural soils,emphasizing the need for future research on changes of greenhouse gas emissions induced by land use change and nitrogen deposition.

关键词： Nitrous oxide Spatiotemporal dynamics Nitrogen deposition Forests Grasslands Data-driven estimates

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Research on Fluctuation Attenuation and Optimization of Passive Residual Heat Removal system Based on Spring Vibrator

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SSRN 2024年

作者： Kang, Zehang Wang, Sipeng Du, Peng Chen, Jin Su, Zhen Zhuang, Kun Department of Nuclear Science and Technology Nanjing University of Aeronautics and Astronautics JiangSu Nanjing211106 China Key Laboratory of Nuclear Technology Application and Radiation Protection in Astronautics Nanjing University of Aeronautics and Astronautics China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The potential for flow instability in passive residual heat removal systems (PRHRS) to result in equipment damage underscored the necessity for the development of effective mitigation strategies. In order to reduce the flow instabilities that occurs in the PRHRS, the idea of a fluctuation attenuation scheme based on a spring vibrator structure had been proposed. The structure was based on pressure pulsation attenuator in hydraulic systems and had been optimized. A model of a spring vibrator fluctuation attenuation pipe section was developed and its fluctuation attenuation effect was verified under specific parameters. Such as branch pipe length, cavity cross-sectional area, spring vibrator position, spring vibrator stiffness coefficient, and piston mass. The impact of these factors on fluctuation attenuation was investigated. The results demonstrated that, under identical inlet fluctuation conditions, the fluctuation peak at outlet of the pipe containing spring vibrator structure decreased. The optimization of the above parameters had been demonstrated to enhance the fluctuation removal effect of the spring vibrator structure. This study presented a novel approach to relieve flow instability in PRHRS. © 2024, The Authors. All rights reserved.

关键词： Vibrators

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