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Identification of Mechanical Properties of Thin-Film Elastoplastic Materials by Machine Learning

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Acta Mechanica Solida Sinica 2023年第1期36卷 13-21页

作者： Xu long Changheng Lu Ziyi Shen Yutai su School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an 710129China

Nanoindentation can effectively evaluate the mechanical properties of materials in the form of bulk and ***,the relationship between the indentation response and the stress–strain curve of thin-film elastoplastic materials is complex and thus difficult to be elucidated using traditional physics-based,empirical or statistical *** this study,the convolutional neural network(CNN),as a practical machine learning method,is adopted and trained to rapidly obtain the mechanical properties of thin-film elastoplastic materials using *** proposed method is targeted for efficiently predicting mechanical properties of thin-film materials from the applied load–penetration depth *** with the power-law model to describe the elastoplastic characteristics,a dataset comprising 228 nanoindentation cases with wide ranges of material properties is numerically simulated by ABAQUS and the corresponding results are adopted for the CNN training and *** addressing the important elastoplastic properties characterized by elastic modulus,yield strength,and hardening exponent,the impacts of CNN’s architecture and training epochs on the predicting performance are investigated in *** varying the number of convolutional layers,the influence of mechanical parameters of thin-film materials on the CNN prediction accuracy is *** results show that compared with the traditional reverse algorithm,CNN can greatly reduce the computational complexity and computation time and has better prediction accuracy for the constitutive parameters of thin-film elastoplastic materials.

关键词： Machine learning Nanoindentation Thin-film material Elastoplasticity Constitutive parameters

Review on Tidal Energy Technologies and Research subjects

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China Ocean Engineering 2020年第1期34卷 137-150页

作者： Chul Hee JO su jin HWANG Department of Naval Architecture and Ocean Engineering Inha University

Tidal current power is one of the promising and reliable renewable energies with the advantage of continuous and predictable resource. It can make stable electricity regardless of weather conditions or seasons all year around. The required technologies for tidal current power in the ocean have been developed for years and now recognized that it could be commercialized after intensive field tests and successful demonstrations. There are several tidal farm development projects in the world, such as the MeyGen project in UK with its commercialization at hand. However, various research subjects in the tidal current energy field are seeking improvements and industrialization of tidal current power in terms of economy and technical reliability. This paper introduces the resource assessment procedure of tidal energy that has been applied in Korea coastal regions. The key research subjects for tidal current power together with the interaction effect of multi-arrangement is described. Also, this paper is to introduce the research output of each subject such as turbine design, experimental validation, turbine interaction and wake, multi-array module, FSI (fluid-structure interaction), and duct application.

关键词： tidal current power resource assessment turbine design experimental validation turbine interaction multi arrangement FSI(fluid-structure interaction)

Effects of thinning on the understory light environment of different stands and the photosynthetic performance and growth of the reforestation species Phoebe bournei

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Journal of Forestry Research 2024年第1期35卷 12-28页

作者： Shicheng su Nianqing jin Xiaoli Wei College of Forestry Guizhou UniversityGuiyang 550025People’s Republic of China Institute for Forest Resources and Environment of Guizhou Guizhou UniversityGuiyang 550025People’s Republic of China

Light levels determine regeneration in stands and a key concern is how to regulate the light environment of different stand types to the requirements of the *** this study,we selected three stands typical in south China(a Cryptomeria japonica plantation,a Quercus acutissima plantation,and a mixed stand of both)and three thinning intensities to determine the best understory light environ-ment for 3-year-old Phoebe bournei *** canopy structure,understory light environment,and photosynthe-sis and growth indicators were assessed following *** improved canopy structure and understory light availability of each stand;species composition was the reason for differences in the understory light *** the same thinning intensity,the mixed stand had the greatest light radiation and most balanced spectral *** photosynthesis and growth were closely related to the light environment;all three stands required heavy thinning to create an effective and sustained understory light *** a suitable understory light environment,the efficiency of light interception,absorption,and use by seedlings was enhanced,resulting in a higher carbon assimilation the main limiting factor was stomatal *** a shade-avoidance signal,red/far-red radia-tion is a critical factor driving changes in photosynthesis and growth of *** seedlings,and a reduction increased light absorption and use capacity and height:diameter *** growth advantage transformed from diameter to height,enabling seedlings to access more *** findings suggest that the regeneration of shade-tolerant species such as *** could be enhanced if a targeted approach to thinning based on stand type was adopted.

关键词： Thinning Understory light environment Phoebe bournei Photosynthetic performance Growth performance

Recent advances in friction and lubrication of graphene and other 2D materials:Mechanisms and applications

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Friction 2019年第3期7卷 199-216页

作者： Lincong LIU Ming ZHOU long jin Liangchuan LI Youtang MO Guoshi su Xiao LI Hongwei ZHU Yu TIAN School of Mechanical Engineering Guangxi University of Science and TechnologyLiuzhou545006China Chengdu Carbon Co. Ltd.No.88South2RoadEconomic and Technological Development ZoneChengdu610100China State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China State Key Laboratory of Tribology Tsinghua UniversityBeijing100084China

Two-dimensional materials having a layered structure comprise a monolayer or multilayers of atomic thickness and ultra-low shear *** high specific surface area,in-plane strength,weak layer-layer interaction,and surface chemical stability result in remarkably low friction and wear-resisting ***,2D materials have attracted considerable *** recent years,great advances have been made in the scientific research and industrial applications of anti-friction,anti-wear,and lubrication of 2D *** this article,the basic nanoscale friction mechanisms of 2D materials including interfacial friction and surface friction mechanisms are *** paper also includes a review of reports on lubrication mechanisms based on the film-formation,self-healing,and ball bearing mechanisms and applications based on lubricant additives,nanoscale lubricating films,and space lubrication materials of 2D materials in ***,the challenges and potential applications of 2D materials in the field of lubrication were also presented.

关键词： two-dimensional materials graphene anti-friction anti-wear lubrication

PPP models and performances from single-to quad-frequency BDS observations

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Satellite Navigation 2020年第1期1卷 179-191页

作者： Shuanggen jin Ke su Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Remote Sensing and Geomatics Engineering Nanjing University of Information Science and TechnologyNanjing 210044China Jiangsu Engineering Center for Collaborative Navigation/Positioning and Smart Applications Nanjing 210044China University of Chinese Academy of Sciences Beijing 100049China

Nowadays,China BeiDou Navigation Satellite System(BDS)has been developed well and provided global services with highly precise positioning,navigation and timing(PNT)as well as unique short-message communication,particularly global system(BDS-3)with higher precision multi-frequency *** precise point positioning(PPP)can provide the precise position,receiver clock,and zenith tropospheric delay(ZTD)with a stand-alone receiver compared to the traditional double differenced relative positioning mode,which has been widely used in PNT,geodesy,meteorology and so ***,it has a lot of challenges for multi-frequency BDS PPP with different strategies and more unknown *** this paper,the detailed PPP models using the single-,dual-,triple-,and quad-frequency BDS observations are presented and ***,BDS system and PPP method are ***,the stochastic models of time delay bias in BDS-2/BDS-3 PPP including the neglection,random constant,random walk and white noise are ***,three single-frequency,four dual-frequency,four triple-frequency and four quad-frequency BDS PPP models are ***,the BDS PPP models progress and performances including theoretical comparison of the models,positioning performances,precise time and frequency transfer,ZTD,inter-frequency bias(IFB)and differential code bias(DCB)are presented and evaluated as well as future *** results show that the multi-frequency BDS observations will greatly improve the PPP performances.

关键词： BDS GNSS PPP IFB ZTD DCB

A low-noise, high-SNR balanced homodyne detector for the bright squeezed state measurement in 1–100 kHz range

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Chinese Physics B 2020年第3期29卷 215-220页

作者： jin-Rong Wang Qing-Wei Wang long Tian jing su Yao-Hui Zheng State Key Laboratory of Quantum Optics and Quantum Optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China

We report a low-noise, high-signal-to-noise-ratio(SNR) balanced homodyne detector based on the standard transimpedance amplifier circuit and the inductance and capacitance combination for the measurement of the bright squeezed state in the range from 1 kHz to 100 kHz. A capacitance is mounted at the input end of the AC branch to prevent the DC photocurrent from entering the AC branch and avoid AC branch saturation. By adding a switch at the DC branch,the DC branch can be flexibly turned on and off on different occasions. When the switch is on, the DC output provides a monitor signal for laser beam alignment. When the switch is off, the electronic noise of the AC branch is greatly reduced at audio-frequency band due to immunity to the impedance of the DC branch, hence the SNR of the AC branch is significantly improved. As a result, the electronic noise of the AC branch is close to -125 dBm, and the maximum SNR of the AC branch is 48 dB with the incident power of 8 mW in the range from 1 kHz to 100 kHz. The developed photodetector paves a path for measuring the bright squeezed state at audio-frequency band.

关键词： quantum optics photodetector low-noise audio band

Verification of neutron-induced fission product yields evaluated by a tensor decompsition model in transport-burnup simulations

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Nuclear Science and Techniques 2023年第2期34卷 190-201页

作者： Qu‑Fei Song long Zhu Hui Guo Jun su School of Nuclear Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Sino‑French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

Neutron-induced fission is an important research object in basic ***,its product yield data are an indispensable nuclear data basis in nuclear engineering and *** fission yield tensor decomposition(FYTD)model has been developed and used to evaluate the independent fission product *** general,fission yield data are verified by the direct comparison of experimental and evaluated ***,such direct comparison cannot reflect the impact of the evaluated data on application scenarios,such as reactor transport-burnup ***,this study applies the evaluated fission yield data in transport-burnup simulation to verify their accuracy and possibility of ***,the evaluated yield data of235U and239Pu are applied in the transport-burnup simulation of a pressurized water reactor(PWR)and sodium-cooled fast reactor(SFR)for *** the reactor operation stage,the errors in pin-cell reactivity caused by the evaluated fission yield do not exceed 500 and 200 pcm for the PWR and SFR,*** errors in decay heat and135Xe and149Sm concentrations during the short-term shutdown of the PWR are all less than 1%;the errors in decay heat and activity of the spent fuel of the PWR and SFR during the temporary storage stage are all less than 2%.For the PWR,the errors in important nuclide concentrations in spent fuel,such as90Sr,137Cs,85Kr,and99Tc,are all less than 6%,and a larger error of 37%is observed *** the SFR,the concentration errors of ten important nuclides in spent fuel are all less than 16%.A comparison of various aspects reveals that the transport-burnup simulation results using the FYTD model evaluation have little difference compared with the reference results using ENDF/B-Ⅷ.0 *** proves that the evaluation of the FYTD model may have application value in reactor physical analysis.

关键词： Fission product yield Tensor decomposition Transport-burnup simulation Machine learning

Finite element method for coupled diffusion-deformation theory in polymeric gel based on slip-link model

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Applied Mathematics and Mechanics(English Edition) 2018年第4期39卷 581-596页

作者： Hengdi su Huixian YAN Bo jin School of Aerospace Engineering and Applied Mechanics Tongji University School of Mechanical and Electrical Engineering Sanming University

A polymeric gel is an aggregate of polymers and solvent molecules, which can retain its shape after a large deformation. The deformation behavior of polymeric gels was often described based on the Flory-Rehner free energy function without considering the influence of chain entanglements on the mechanical behavior of gels. In this paper,a new hybrid free energy function for gels is formulated by combining the EdwardsVilgis slip-link model and the Flory-Huggins mixing model to quantify the time-dependent concurrent process of large deformation and mass transport. The finite element method is developed to analyze examples of swelling-induced deformation. Simulation results are compared with available experimental data and show good agreement. The influence of entanglements on the time-dependent deformation behavior of gels is also *** study of large deformation kinetics of polymeric gel is useful for diverse applications.

关键词： polymeric gel finite element method slip-link model large deformation mass transport kinetics

Highly Aromatic Norditerpenoid Heterodimers and Monomers from Trigonostemon fragilis

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Engineering 2024年第7期38卷 144-154页

作者： Jun-su Zhou long Cheng Yuan Gao Zhan-Peng Ge Bin Zhou jing-Ya Li jin-Xin Zhao Jian-Min Yue State Key Laboratory of Drug Research Shanghai Institute of Materia MedicaChinese Academy of SciencesShanghai 201203China Shandong Laboratory of Yantai Drug Discovery Bohai Rim Advanced Research Institute for Drug DiscoveryYantai 264117China

Four new norditerpenoid heterodimers with different dimerization patterns-namely,trigofragiloids A-C(denoted as compounds 1-3)and(+)-and(-)-trigofragiloid D(compound 4)-and three new phenanthrenone norditerpenoids-namely,trigofragiloids E-G(compounds 5-7)-were isolated from Trigonostemon *** 1 and 2 feature a novel heterodimeric carbon skeleton formed by the conjugation of a tetra-norditerpenoid and an ennea-norditerpenoid;they have been identified as class 2 atropisomers by means of quantum chemical *** 3 is an unprecedented phenylpropanoid-norditerpenoid adduct with a new dimerization ***(+)-and(-)-4 are the first example of S-shaped 1,4-dioxane-fused norditerpenoid *** by the structure elucidation of compound 4,two co-occurring analogues,actephilol A and epiactephilol A,were structurally revised as a pair of geometrical isomers and were identified as two pairs of enantiomers,(+)-and(-)-8 and(+)-and(-)-9,*** structures were characterized using a combined ***,compound 7 exhibits remarkable adenosine triphosphate-citrate lyase(ACLY)inhibition with a halfmaximal inhibition concentration(IC50)value of(0.46±0.11)lmol·L^(-1),as active as the positive control BMS-303141,and a molecular docking study offers deep insight into the interaction between compound 7 and ACLY.

关键词： Norditerpenoid heterodimer Trigonostemon fragilis Euphorbiaceae Trigofragiloid Structural revision Adenosine triphosphate-citrate lyase(ACLY) inhibitory activity