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Surrogate modeling for unsaturated infiltration via the physics and equality-constrained artificial neural networks

Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2282-2295页

作者： peng Lan Jingjing Su sheng Zhang School of Civil Engineering Central South UniversityChangsha410075China Discipline of Civil Surveying and Environmental EngineeringPriority Research Centre for Geotechnical Science and EngineeringThe University of NewcastleCallaghanNSW2308Australia Qinghai University Qinghai810016China

Machine learning(ML)provides a new surrogate method for investigating groundwater flow dynamics in unsaturated *** pure data-driven methods(*** neural network,DNN)can provide rapid predictions,but they do require sufficient on-site data for accurate training,and lack interpretability to the physical processes within the *** this paper,we provide a physics and equalityconstrained artificial neural network(PECANN),to derive unsaturated infiltration solutions with a small amount of initial and boundary *** takes the physics-informed neural network(PINN)as a foundation,encodes the unsaturated infiltration physical laws(*** equation,RE)into the loss function,and uses the augmented Lagrangian method to constrain the learning process of the solutions of RE by adding stronger penalty for the initial and boundary *** unsaturated infiltration cases are designed to test the training performance of PECANN,***-dimensional(1D)steady-state unsaturated infiltration,1D transient-state infiltration,two-dimensional(2D)transient-state infiltration,and 1D coupled unsaturated infiltration and *** predicted results of PECANN are compared with the finite difference solutions or analytical *** results indicate that PECANN can accurately capture the variations of pressure head during the unsaturated infiltration,and present higher precision and robustness than DNN and *** is also revealed that PECANN can achieve the same accuracy as the finite difference method with fewer initial and boundary training ***,we investigate the effect of the hyperparameters of PECANN on solving RE *** provides an effective tool for simulating unsaturated infiltration.

关键词： Richards equation(RE) Unsaturated infiltration Data-driven solutions Numerical modeling Machine learning(ML)

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Nonlinear metamaterial enabled aeroelastic vibration reduction of a supersonic cantilever wing plate

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Applied Mathematics and Mechanics(English Edition) 2024年第10期45卷 1749-1772页

作者： peng sheng Xin FANG Dianlong YU Jihong WEN Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and TechnologyNational University of Defense TechnologyChangsha 410073China

The violent vibration of supersonic wings threatens aircraft *** paper proposes the strongly nonlinear acoustic metamaterial(NAM)method to mitigate aeroelastic vibration in supersonic wing *** employ the cantilever plate to simulate the practical behavior of a *** aeroelastic vibration model of the NAM cantilever plate is established based on the mode superposition method and a modified third-order piston *** aerodynamic properties are systematically studied using both the timedomain integration and frequency-domain harmonic balance *** presenting the flutter and post-flutter behaviors of the NAM wing,we emphasize more on the preflutter broadband vibration that is prevalent in *** results show that the NAM method can reduce the low-frequency and broadband pre-flutter steady vibration by 50%-90%,while the post-flutter vibration is reduced by over 95%,and the critical flutter velocity is also slightly *** clarified,the significant reduction arises from the bandgap,chaotic band,and nonlinear resonances of the NAM *** reduction effect is robust across a broad range of parameters,with optimal performance achieved with only 10%attached *** work offers a novel approach for reducing aeroelastic vibration in aircraft,and it expands the study of nonlinear acoustic/elastic metamaterials.

关键词： nonlinear acoustic metamaterial(NAM) hypersonic aeroelastic vibration vibration reduction fluid-structure interaction

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Fourth-order phase-field modeling for brittle fracture in piezoelectric materials

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 837-856页

作者： Yu TAN Fan peng chang LIU Daiming peng Xiangyu LI State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Science Chang'an UniversityXi'an 710064China Applied Mechanics and Structure Safety Key Laboratory of Sichuan Province School of Mechanics and Aerospace EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Failure analyses of piezoelectric structures and devices are of engineering and scientific *** this paper,a fourth-order phase-field fracture model for piezoelectric solids is developed based on the Hamilton *** typical electric boundary conditions are involved in the present model to characterize the fracture behaviors in various physical situations.A staggered algorithm is used to simulate the crack *** polynomial splines over hierarchical T-meshes(PHT-splines)are adopted as the basis function,which owns the *** numerical simulations are performed to study the influence of the electric boundary conditions and the applied electric field on the fracture behaviors of piezoelectric *** electric boundary conditions may influence crack paths and fracture loads *** present research may be helpful for the reliability evaluation of the piezoelectric structure in the future applications.

关键词： isogeometric analysis(IGA) brittle fracture fourth-order phase-field model piezoelectric solid

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Effects of water salinity and content on particle size distribution and soil strength

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Journal of Environmental Science and Engineering 2009年第1期3卷 24-28页

作者： peng chang-sheng LOWG Kathleen ZHANG Qian College of Environmental Science and Engineering Ocean University of China Qingdao 266100 China Instituto de Metalurgia Universidad Autonoma de San Luis Potosi San Luis Potosi 78210 Mexico Department of Civil and Environmental Engineering University of California Berkeley San Jose 95132 USA

The effect of NaCl on soil strength was investigated in this project based on salinity concentrations of 0 g/L, 5 g/L, 20 g/L, and 50 g/L as well as varying water contents of 15%-20%. Laser particle size analyzer was also performed to explain possible effects. From particle size analysis and strength tests, it is hypothesized that the strength of the soil is increased with the addition of certain salinity concentrations until there are reversed effects, which is between 20 g/L and 50 g/L from our study. The increase of strength is suggested to be the affect of a greater variety of particle sizes. Since NaCI plays a role in the particle size distribution, it also plays a role in the strength of soils. The degree of the effect of the water content also differs from concentrations, and could be due to the variation of hydration film thickness on particles, which is affected by the ions introduced from water.

关键词： water salinity water content particle size distribution soil strength hydration film

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Sex-biased adaptation shapes uniparental gene pools in Tibetans

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Science China(Life Sciences) 2024年第3期67卷 611-613页

作者： Min-sheng peng Ya-Ping Zhang State Key Laboratory of Genetic Resources and Evolution Kunming Institute of ZoologyChinese Academy of SciencesKunming 650201China KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases Kunming Institute of ZoologyChinese Academy of SciencesKunming 650201China Kunming College of Life Science University of Chinese Academy of SciencesKunming 650204China State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan School of Life SciencesYunnan UniversityKunming 650091China

During the past two decades, a series of archaeological and genetic investigations substantially improve our perception of the hominin settlement of the Tibetan Plateau(Zhang et al., 2022). In addition to the identifi... 详细信息

关键词： Tibetan Plateau altitude

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Catalytically generated noncovalent ammonium dienolate:a versatile platform for the development of organocatalytic asymmetric cascade reactions

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Science China Chemistry 2024年第8期67卷 2524-2546页

作者： Jun-Bing Lin Dong-sheng Ji peng-Fei Xu State Key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical EngineeringLanzhou UniversityLanzhou 730000China Shaanxi Key Laboratory of Chemical Reaction Engineering College of Chemistry and Chemical EngineeringYan’an UniversityYan’an 716000China

Organocatalytic cascade reactions represent a powerful strategy for the rapid construction of complex chiral molecules with multiple stereocenters from simple substrates under mild conditions. The intriguing structural feature and diverse reactivity of catalytically generated dienolate species render them competent and versatile intermediates for the development of practical and valuable cascade reactions. Over the past years, a plethora of innovative and pioneering noncovalent ammonium dienolatemediated cascade reactions have been designed and implemented under the catalysis of chiral organocatalysts, making dienolate activation a general, robust, and complementary method for the functionalization of unsaturated carbonyl compounds and related substances. This review illustrates the recent advances in organocatalytic noncovalent ammonium dienolate-mediated cascade reactions(mainly from 2010 to 2023), including the cascade transformations of ammonium dienolates directly generated from unsaturated ketone/aldehyde, ester/lactone/azlactone, amide/lactam/pyrazolone/oxindole, and alkylidene nitrile compounds. The contents are arranged based on the reaction types of the ammonium dienolates, with an emphasis on cascade 2,5-, 3,5-, and 4,5-difunctionalizations of these intermediates. Furthermore, other cascade reactions involving the 1,3-, 2,3-, and even more complex 3,4,5-reactivities of ammonium dienolates were also discussed. The reaction pathway, reaction stereoinduction, and synthetic applications of the ammonium dienolate-mediated cascade reactions were highlighted throughout the article. As a stimulating and ever-growing research area, the organocatalytic noncovalent ammonium dienolate-mediated cascade reactions are expected to continue demonstrating their magic power for constructing chiral targets in the future and further expanding the boundaries of asymmetric catalysis.

关键词： organocatalysis asymmetric catalysis ammonium dienolate cascade reaction difunctionalization

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Friction of graphene on a substrate with a cavity defect

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Science China(Technological Sciences) 2024年第9期67卷 2834-2841页

作者： ZHOU peng HUO ZhanLei chang TienChong Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai Frontier Science Center of MechanoinformaticsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China The Center for Computational Mechanics and Engineering Applications Provincial Mechanics Experimental Teaching Demonstration CenterSchool of Civil EngineeringHebei University of EngineeringHandan 056038China Shanghai Institute of Aircraft Mechanics and Control Tongji UniversityShanghai 200092China Joint-Research Center for Computational Materials Zhejiang LaboratoryHangzhou 311100China

The frictional behavior of supported graphene is known to be influenced by the physical properties and surface morphologies of the underlying substrate. However, it is unclear how a surface defect on the substrate affects the friction of supported graphene,and it is even unknown how to define the defect-induced friction force in this context. Here we conduct molecular dynamics(MD) simulations to investigate the friction between a square diamond slider and a graphene sheet supported by a copper substrate with a surface cavity defect. Our results demonstrate that the defect-induced friction exhibits a nonlinear increase with cavity size, while it decreases nonlinearly with slider size. We propose that the definition of defect-induced friction can be linked to the increase in friction work over the length of the slider, and is closely correlated to the defect-induced relative change in indentation depth and the ratio of the cavity area to the contact area. These findings provide a comprehensive evaluation of the impact of a substrate cavity defect on the friction of supported graphene and offer insights that may have broader implications for understanding defect-induced friction in other two-dimensional materials.

关键词： friction graphene underneath substrate cavity defect

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Dynamic kinetic stereodivergent transformations of propargylic ammonium salts via dual nickel and copper catalysis

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Chinese Chemical Letters 2024年第8期35卷 265-269页

作者： Ruilong Geng Lingzi peng chang Guo Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry University of Science and Technology of ChinaHefei 230026China

The dynamic kinetic asymmetric transformation of racemic propargylic ammonium salts with prochiral aldimine esters through a stereodivergent propargylation is catalyzed by dual nickel and copper ***,a diverse range of optically activeα-quaternary amino esters were produced via C-N bond cleavage with high reaction efficiency and stereoselectivity(up to>99%ee).By selection of the appropriate pair-wise combination of catalyst configurational isomers,all four possible stereoisomers of the corresponding propargylation products are obtained in high yields with excellent regio-,diastereo-,and enantioselectiv-ities.

关键词： Stereodivergent propargylation Dual catalysis C-N bond cleavage Azaomethine ylides Internal propargylic ammonium salts Excellent stereoselectivity

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中部地区农村劳动力跨省流动选择的影响因素分析——基于安徽省6县582个农户的问卷调查

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华中科技大学学报（社会科学版） 2014年第5期28卷 132-140页

作者：彭长生安庆师范学院经济与管理学院

基于安徽省6县582个农户的问卷调查数据,构建二元Logistic模型讨论子女性别偏好和状态依赖假定下中部地区农村劳动力跨省流动选择的影响因素。研究发现,户主的年龄、非务工收入对劳动力跨省流动有显著的负向影响;户主是否参加农村居民... 详细信息

基于安徽省6县582个农户的问卷调查数据,构建二元Logistic模型讨论子女性别偏好和状态依赖假定下中部地区农村劳动力跨省流动选择的影响因素。研究发现,户主的年龄、非务工收入对劳动力跨省流动有显著的负向影响;户主是否参加农村居民养老保险、户主是否参加新农合医疗保险、户主学历为初中、与县城的距离等变量对家庭户主的跨省流动产生显著的正向影响;农户家庭是否有男孩、头孩是否为女孩等子女性别特征变量对家庭户主的跨省流动产生十分显著的正向影响。实证分析结果表明,子女性别结构是农户家庭劳动决策的最为重要的影响因素,男孩偏好下更高的抚养成本成为户主跨省流动就业的重要激励,但这一家庭特征因素背后仍然脱离不开经济动因。

关键词：农村劳动力跨省流动男孩偏好子女性别结构状态依赖

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CP violation of baryon decays with Nπrescatterings

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Chinese Physics C 2024年第10期48卷 1-10页

作者： Jian-peng Wang Fu-sheng Yu MOE Frontiers Science Center for Rare Isotopes and School of Nuclear Science and TechnologyLanzhou UniversityLanzhou 730000China

There is a long-standing puzzle that the CP violation(CPV)in the baryon systems has never been wellestablished in experiments,while the CPV of mesons have been observed by *** this paper,we propose thatthe CpV of baryon decays can be generated with the rescatterings of a nucleon and a pion into some final states,i.e Nπ→Nπor Nππ.Benelited by the fruitful data of Nπscatterings,we can model-independently analyse the strongphases of b-baryon decays using the partial wave amplitudes of Nπ*** the most difficult problemof non-perturbative dynamics,it makes a great advantage to predict the CpV of baryon decays with a relatively *** understanding of the decay *** study the processes of∧_(b)^(0)→(pπ^(+)π^(-))h^(-)and(pπ^(0))h^(-)with h=πor *** is found that the global CPV of the above processes in the invariant mass regions of Nπscatterings are at theorder of several *** importantly,the local CPV in some regions of the Dalitz plots can reach the order of 10%,or be even *** the predicted results and the experimental data samples,we strong suggest tomeasure the CPV of∧_(b)^(0)→(pπ^(+)π^(-))K^(-),which has a large possibility to achieve the first observation of CPV in thebaryon system.

关键词： CP violation baryon decays Nπscatterings

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