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Isogeometric Analysis for the Arbitrary AFG Microbeam with Two-Phase Nonlocal Stress-Driven Model

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Acta Mechanica Solida Sinica 2024年第2期37卷 341-360页

作者： Pei-Liang Bian Zhaowei Liu Hai qing Tiantang yu Department of Engineering Mechanics Hohai UniversityNanjing211100China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Scale effects play critical roles in the mechanical responses of *** isogeometric analysis was developed here to investigate the mechanical responses of an axially functionally graded *** Euler–Bernoulli beam model was utilized,and size effects in the structure were modeled with a stress-driven two-phase local/nonlocal integral *** governing equation of microstructures was given in an equivalent differential form with two additional constitutive boundary *** framework was verified and utilized to analyze the microbeam’s static and dynamic mechanical *** present work showed great potential for modeling various types of functionally graded microstructures.

关键词： Isogeometric analysis Size effect Functionally graded material Nonlocal theory Euler-Bernoulli beam

Generative deep-learning-embedded asynchronous structured light for three-dimensional imaging

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Advanced Photonics 2024年第4期6卷 45-58页

作者： Lei Lu Chenhao bu Zhilong Su Banglei Guan Qifeng yu Wei Pan qinghui Zhang Henan University of Technology College of Information Science and EngineeringZhengzhouChina Shanghai University Shanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai Key Laboratory of Mechanics in Energy EngineeringShanghaiChina Shaoxing Research Institute of Shanghai University ShaoxingChina National University of Defense Technology College of Aerospace Science and EngineeringChangshaChina OPT Machine Vision Tech Co. Ltd.Department of Research and DevelopmentDongguanChina

Three-dimensional(3D)imaging with structured light is crucial in diverse scenarios,ranging from intelligent manufacturing and medicine to ***,current structured light methods rely on projector-camera synchronization,limiting the use of affordable imaging devices and their consumer *** this work,we introduce an asynchronous structured light imaging approach based on generative deep neural networks to relax the synchronization constraint,accomplishing the challenges of fringe pattern aliasing,without relying on any a priori constraint of the projection *** overcome this need,we propose a generative deep neural network with U-Net-like encoder-decoder architecture to learn the underlying fringe features directly by exploring the intrinsic prior principles in the fringe pattern *** train within an adversarial learning framework and supervise the network training via a statisticsinformed loss *** demonstrate that by evaluating the performance on fields of intensity,phase,and 3D *** is shown that the trained network can separate aliased fringe patterns for producing comparable results with the synchronous one:the absolute error is no greater than 8μm,and the standard deviation does not exceed 3μ*** results on multiple objects and pattern types show it could be generalized for any asynchronous structured light scene.

关键词： structured light fringe pattern projection asynchrony deep learning generative neural networks three-dimensional imaging

Cosmological interpretation for the stochastic signal in pulsar timing arrays

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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 43-50页

作者： yu-Mei Wu Zu-Cheng Chen qing-Guo Huang School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Department of Astronomy Beijing Normal UniversityBeijing 100875China Advanced Institute of Natural Sciences Beijing Normal UniversityZhuhai 519087China Department of Physics and Synergistic Innovation Center for Quantum Effects and Applications Hunan Normal UniversityChangsha 410081China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China

The pulsar timing array(PTA)collaborations have recently reported compelling evidence for a stochastic signal consistent with a gravitational-wave *** this paper,we combine the latest data sets from NANOGrav,PPTA,and EPTA to explore cosmological interpretations for the PTA signal from first-order phase transitions,domain walls,and cosmic strings,*** find that the domain wall model is strongly disfavored with the Bayes factors compared with the first-order phase transitions and cosmic strings being 1/90 and 1/189,respectively,breaking the degeneracy among these models in individual data *** also find that:(1)a strong phase transition at temperatures below the electroweak scale is favored,and the bubble collisions make the dominant contribution to the energy density spectrum;(2)a small reconnection probability p<1.55×10^(-1)allowed by strings in(super)string theory is favored at the 95%confidence level,and ground-based detectors can further constrain the parameter space.

关键词： puslar timing arrays gravitational-wave background first-order phase transitions domain walls cosmic strings

High-Superelasticity NiTi Shape Memory Alloy by Directed Energy Deposition-Arc and Solution Heat Treatment

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 132-144页

作者： Junyi Ma Lin yu qing Yang Jie Liu Lei Yang State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan430070China School of Transportation and Logistics Engineering Wuhan University of TechnologyWuhan430074China

Directed energy deposition-arc(DED-Arc)technology has the advantages of simple equipment,low manufacturing cost and high deposition rate,while the use of DED-Arc has problems of microstructure inhomogeneity,position dependence of macroscopic mechanical properties and ***,it is necessary to carry out a subsequent heat treatment to improve its microstructure uniformity,mechanical properties and *** this investigation,the DED-Arc 15-layer NiTi alloy thin-walled parts with the solution treatment at different process parameters were studied to analyze the effects of solution heat treatment on microstructure,phase composition,phase transformation,microhardness,tensile and *** temperature range of solution treatment is 800-1050℃,and the treatment time range is 1-5.5 *** results show that after solution treatment at 800℃/1 h,the content of precipitated phase decreases,the grain is refined,the microhardness increases,and the mechanical properties in the 0°direction are *** strain recovery rate after 10 tensile cycles has increased from 37.13%(as-built)to 49.25%(solid solution treatment).This research provides an effective post treatment method for high-performance DED-Arc NiTi shape memory alloys.

关键词： Directed energy deposition-arc(DED-Arc) Cold metal transfer(CMT) NiTi shape memory alloys Microstructure Phase transformation Solution heat treatment

Multi-physical fields distribution in billet during helical electromagnetic stirring:A numerical simulation research

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China Foundry 2024年第1期21卷 51-59页

作者： Dong Pan qing-tao Guo Kai-lun Zhang Fu-zhi yu yu-ying Li yu-bao Xiao State Key Laboratory of Metal Materials for Marine Equipment and Application Anshan 114009LiaoningChina Ansteel Beijing Research Institute Co. Ltd.Beijing 102200China

Electromagnetic stirring is one of the widely applied techniques to modify the quality of casting *** from conventional rotate stirring,the helical stirring is more professional in assisting multi-dimensional flow of molten metal and eliminating solidification *** this study,the single-winding helical stirring(SWHS)was introduced,offering advantages such as smaller volume and lower electromagnetic shielding compared to traditional helical stirring *** a comprehensive numerical simulation,the stirring parameters of SWHS were adjusted to yoke inclination angle of 43°and frequency of 12 *** higher electromagnetic force and flow velocity in drawing direction,as well as the lower temperature gradient induced by the SWHS,are positive factors for homogeneous solidification of *** experimental results on Al-8%Si alloy and 0.4%C-1.1%Mn steel demonstrate that compared to rotate stirring,the SWHS process can induce better billet quality and is more effective in accelerating the equiaxed expansion and reducing element *** SWHS process can enhance the equiaxed ratio of the billet by 58.3%and reduce segregation degree of carbon element by 10.97%.Consequently,SWHS holds great promise as a potential approach for improving the quality of continuous casting billets.

关键词： billet electromagnetic stirring helical solidification element segregation numerical simulation

Single depth image 3D face reconstruction via domain adaptive learning

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Frontiers of Computer Science 2024年第1期18卷 259-261页

作者： Xiaoxu CAI Jianwen LOU Jiajun bu Junyu DONG Haishuai WANG Hui yu College of Computer Science and Technology Zhejiang UniversityHangzhou 310013China School of Creative Technologies University of PortsmouthPortsmouth PO12DJUK College of Computer Science and Technology Ocean University of ChinaQingdao 266100China

1 Introduction In this paper,we propose a novel domain-adaptive reconstruction method that effectively leverages deep learning and synthetic data to achieve robust 3D face reconstruction from a single depth *** method applies two domain-adaptive neural networks for predicting head pose and facial shape,*** networks undergo training with a customized domain adaptation strategy,using a combination of auto-labeled synthetic and unlabeled real data.

关键词： networks image learning

Helmholtz decomposition with a scalar Poisson equation in elastic anisotropic media

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Petroleum Science 2024年第3期21卷 1597-1610页

作者： Xin-yu Fang Gang Yao qing-qing Zheng Ping-Min Zhang Di Wu Feng-Lin Niu State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China Unconventional Petroleum Research Institute China University of Petroleum(Beijing)Beijing102249China Department of Mathematics College of ScienceChina University of Petroleum(Beijing)Beijing102249China College of Geophysics China University of Petroleum(Beijing)Beijing102249China Department of Earth Environmental and Planetary SciencesRice UniversityHoustonTX77005UA

P-and S-wave separation plays an important role in elastic reverse-time *** can reduce the artifacts caused by crosstalk between different modes and improve image *** addition,P-and Swave separation can also be used to better understand and distinguish wave types in complex *** present,the methods for separating wave modes in anisotropic media mainly include spatial nonstationary filtering,low-rank approximation,and vector Poisson *** of these methods require multiple Fourier transforms or the calculation of large matrices,which require high computational costs for problems with large *** this paper,an efficient method is proposed to separate the wave mode for anisotropic media by using a scalar anisotropic Poisson operator in the spatial *** 2D problems,the computational complexity required by this method is 1/2 of the methods based on solving a vector Poisson ***,compared with existing methods based on pseudoHelmholtz decomposition operators,this method can significantly reduce the computational *** examples also show that the P and S waves decomposed by this method not only have the correct amplitude and phase relative to the input wavefield but also can reduce the computational complexity significantly.

关键词： Anisotropic media Scalar anisotropic Poisson equation Improved elastic wavefield decomposition

Potential for soil carbon sequestration under conservation agriculture in a warming climate

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Science bulletin 2024年第13期69卷 2030-2033页

作者： Lijun yu Wen Zhang Jingjing Liu Wenjuan Sun qing Zhang State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Anyang Meteorological Service Anyang 455000China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China

Agricultural soil has numerous links with climate *** comprises a substantial part of farming systems that are affected by climate change and can significantly impact food security[1].An increase in the soil carbon(C)stock is associated with an increase in the crop ***,agricultural soil remains a source for all three major greenhouse gases(GHGs),i.e.,carbon dioxide(CO_(2)),methane and nitrous oxide,which contributes directly to climate *** addition,enhancing soil C sequestration in agricultural land could offset GHG emissions,promote more sustainable and climate-resilient agricultural systems.

关键词： soil warming agricultural

Comparison and Verification of Coherent Doppler Wind Lidar and Radiosonde Data in the Beijing Urban Area

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Advances in Atmospheric Sciences 2024年第11期41卷 2203-2214页

作者： Zexu LUO Xiaoquan SONG Jiaping YIN Zhichao bu yubao CHEN Yongtao yu Zhenlu ZHANG College of Marine Technology Faculty of Information Science and EngineeringOcean University of ChinaQingdao 266100China Laboratory for Regional Oceanography and Numerical Modeling Laoshan LaboratoryQingdao 266237China qingdao Leice Transient Technology Co.LTD Qingdao 266100China CMA Meteorological Observation Centre Beijing 100081China Beijing Municipal Meteorological Observation Center Beijing 102600China qingdao Meteorological Comprehensive Support Center Qingdao 266003China

As a new type of wind field detection equipment, coherent Doppler wind lidar(CDWL) still needs more relevant observation experiments to compare and verify whether it can achieve the accuracy and precision of traditional observation equipment in urban areas. In this experiment, a self-developed CDWL provided four months of observations in the southern Beijing area. After the data acquisition time and height match, the wind profile data obtained based on a Doppler beam swinging(DBS) five-beam inversion algorithm were compared with radiosonde data released from the same location. The standard deviation(SD) of wind speed is 0.8 m s^(–1), and the coefficient of determination R~2 is 0.95. The SD of the wind direction is 17.7° with an R~2 of 0.96. Below the height of the roughness sublayer(about 400 m), the error in wind speed and wind direction is significantly greater than the error above the height of the boundary layer(about 1500 m). For the case of wind speeds less than 4 m s^(–1), the error of wind direction is more significant and is affected by the distribution of surrounding buildings. Averaging at different height levels using suitable time windows can effectively reduce the effects of turbulence and thus reduce the error caused by the different measurement methods of the two devices.

关键词： coherent Doppler wind lidar radiosonde wind measurement urban boundary layer