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Chien-physics-informed neural networks for solving singularly perturbed boundary-layer problems

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Applied Mathematics and mechanics(English Edition) 2024年第9期45卷 1467-1480页

作者： Long WANG Lei zhang guowei he The state key Laboratory of Nonlinear {3. Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering sciences University of Chinese Academy of SciencesBeijing 100049China

A physics-informed neural network(PINN)is a powerful tool for solving differential equations in solid and fluid ***,it suffers from singularly perturbed boundary-layer problems in which there exist sharp changes caused by a small perturbation parameter multiplying the highest-order *** this paper,we introduce Chien's composite expansion method into PINNs,and propose a novel architecture for the PINNs,namely,the Chien-PINN(C-PINN)*** novel PINN method is validated by singularly perturbed differential equations,and successfully solves the wellknown thin plate bending *** particular,no cumbersome matching conditions are needed for the C-PINN method,compared with the previous studies based on matched asymptotic expansions.

关键词： physics-informed neural network(PINN) singular perturbation boundarylayer problem composite asymptotic expansion

Large-eddy simulation of flows past a flapping airfoil using immersed boundary method

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Science china(Physics,mechanics & Astronomy) 2010年第6期53卷 1101-1108页

作者： yang xiaolei,he guowei & {3. xing The state key Laboratory of Nonlinear mechanics,institute of mechanics,chinese academy of sciences,beijing 100190,china The state key Laboratory of Nonlinear {3. Institute of Mechanics Chinese Academy of Sciences Beijing China

The numerical simulation of flows past flapping foils at moderate Reynolds numbers presents two challenges to computational fluid dynamics: turbulent flows and moving boundaries. The direct forcing immersed boundary(IB) method has been developed to simulate laminar flows. However,its performance in simulating turbulent flows and transitional flows with moving boundaries has not been fully evaluated. In the present work,we use the IB method to simulate fully developed turbulent channel flows and transitional flows past a stationary/plunging SD7003.airfoil. To suppress the non-physical force oscillations in the plunging case,we use the smoothed discrete delta function for interpolation in the IB method. The results of the present work demonstrate that the IB method can be used to simulate turbulent flows and transitional flows with moving boundaries.

关键词： transitional flows moving boundary immersed boundary method smoothed discrete delta function

Characterization of plastic flow in two Zr-based bulk metallic glasses

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Science china(Technological sciences) 2006年第4期49卷 414-424页

作者： xing Dongmei1,2, zhang Taihua1, LI Weihuo3.& WEI Bingchen3.1. {3. key Laboratory of Nonlinear mechanics (LNM), institute of mechanics, chinese academy of Sci- ences, beijing 100080, china 2. College of Physics and Electronic Information Science, Tianjin Normal University, Tianjin 3.0074, china 3. National Microgravity Laboratory, institute of mechanics, {13., beijing 100080, china state key Laboratory of Nonlinear mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing China College of Physics and Electronic Information Science Tianjin Normal University Tianjin China National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing China

Plastic deformation behaviors of Zr65Al10Ni10Cu15 and Zr52.5Al10Ni10Cu15Be12.5 bulk metallic glasses (BMGs) are studied by using the depth-sensing nanoindentation, microindentation and uniaxial compression. The Be-containing BMG exhibits a signifi- cantly improved overall plastic strain compared with the Be-free alloy during compressive tests. Both BMGs show a loading-rate-dependent serrated flow during nanoindentation measurements, but the Be-containing alloy exhibits a much lower critical loading rate for the disappearance of the serration than the Be-free BMG. The shear band patterns de- veloped during plastic deformation are investigated by microindentation technique, wherein much higher shear band density is found in the Be-containing alloy than in the Be-free alloy, indicating an easier nucleation of shear bands in the former BMG. The dif- ference in the plastic deformation behavior of the two BMGs can be explained by a free volume model.

关键词： Bulk metallic glass, plastic deformation, shear band, nanoindentation.

Improved genome annotation of Brassica oleracea highlights the importance of alternative splicing

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Horticultural Plant Journal 2024年第4期10卷 961-970页

作者： Yinqing yang Lei zhang Qi Tang Lingkui zhang {3. Li Shumin Chen Kang zhang Ying Li Xilin Hou Feng Cheng state key Laboratory of Crop Genetics and Germplasm Enhancement College of HorticultureNanjing Agricultural UniversityNanjing 210095China state key Laboratory of Vegetable Biobreeding Institute of Vegetables and FlowersChinese Academy of Agricultural SciencesKey Laboratory of Biology and Genetic Improvement of Horticultural Crops of the Ministry of Agriculture and Rural AffairsSino-Dutch Joint Laboratory of Horticultural GenomicsBeijing 100081China

Brassica oleracea has been developed into many important crops,including cabbage,kale,cauliflower,broccoli and so *** genome and gene annotation of cabbage(cultivar JZS),a representative morphotype of ***,has been widely used as a common reference in biological *** its genome assembly has been updated twice,the current gene annotation still lacks information on untranslated regions(UTRs)and alternative splicing(AS).here,we constructed a high-quality gene annotation(JZSv3.using a full-length transcriptome acquired by nanopore sequencing,yielding a total of 59452 genes and 75684 ***,we re-analyzed the previously reported transcriptome data related to the development of different tissues and cold response using JZSv3.as a reference,and found that 3.43.out of 11908 differentially expressed genes(DEGs)underwent AS during the development of different tissues and 3.9 out of 903.cold-related genes underwent AS in response to cold ***,we also identified many AS genes,including BolLHCB5 and BolHSP70,that displayed distinct expression patterns within variant transcripts of the same gene,highlighting the importance of JZSv3.as a pivotal reference for AS ***,JZSv3.provides a valuable resource for exploring gene function,especially for obtaining a deeper understanding of AS regulation mechanisms.

关键词： Brassica oleracea Oxford nanopore technologies Gene annotation Alternative splicing

Interfacial assembly of 2D polydopamine/graphene heterostructures with well-defined mesopore and tunable thickness for high-energy planar micro-supercapacitors

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chinese Chemical Letters 2024年第7期35卷 439-444页

作者： Jieqiong Qin Zhi yang Jiaxin Ma Liangzhu zhang Feifei xing Hongtao zhang Shuxia Tian Shuanghao Zheng Zhong-Shuai Wu College of Science Henan Agricultural UniversityZhengzhou 450002China state key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China University of chinese academy of sciences Beijing 100049China Mechanical and Electrical Engineering institute Zhengzhou University of Light IndustryZhengzhou 450002China

Two-dimensional(2D)mesoporous pseudocapacitive polymer/graphene heterostructures combine the advanced merits of 2D materials and mesoporous materials,possessing unique nanosheet structure,large specific surface area(SSA),abundant oxygen/nitrogen-containing groups,desirable electrical conductivity and admirable electrochemical redox activity,and hold great potential for constructing high-performance planar micro-supercapacitors(MSCs).herein,we demonstrate the interfacial assembly of 2D mesoporous polydopamine/graphene(mPDG)heterostructures with well-defined mesopore structure(12 nm)and adjustable thickness(7.5–14.1 nm)for planar high-energy pseudocapacitive *** to medium thickness,exposed mesopore of 12 nm and large SSA of 108 m^(2)/g,the m PDG with 10.8 nm thickness reveals prominent mass capacitance of 419 F/g and impressive cycling stability with~96%capacitance retention after 5000 ***,the symmetric mPDG-based MSCs with“water-in-salt”gel electrolyte present wide voltage window of 1.6 V,superior volumetric energy density of 11.5 mWh/cm^(3.,outstanding flexibility and self-integration ***,this work offers a new platform of controllably synthesizing 2D mesoporous heterostructures for high-performance MSCs.

关键词： 2D materials Mesopores heterostructures Polydopamine High energy density Micro-supercapacitors

New dating indicates intermittent human occupation of the Nwya Devu Paleolithic site on the high-altitude central Tibetan Plateau during the past 45,000 years

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Science china Earth sciences 2024年第2期67卷 531-551页

作者： Junyi GE Xiaoling zhang Shejiang WANG Linhui LI Wei he Yingshuai JIN Peiqi zhang Bing XU Chenglong DENG John WOLSEN Zhengtang GUO xing GAO institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of SciencesBeijing 100044China University of the chinese academy of sciences Beijing 100049China Tibetan Cultural Relics Conservation institute Lhasa 850000China key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of Sciences.Beijing 100029China state key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China School of Anthropology University of ArizonaTucson85721USA

The timing and mechanisms of the human occupation of the demanding high-altitude Tibetan Plateau environment are of great ***,we report on our reinvestigations and dating of the Nwya Devu site,located nearly 4600 meters above sea level on the central Tibetan Plateau.A new microblade techno-complex was identified on a lower lake shore at this site,distinct from the previously reported blade tool *** two lithic assemblages were dated to 45.6±2.6 and10.3.0.5 ka using optically stimulated luminescence and accelerator mass spectrometry^(14)C *** represent,respectively,the earliest known Paleolithic and microlithic sites on the interior Tibetan Plateau,indicating multiple occupation episodes of hunter-gatherers during the past 45 *** studies reveal that relatively stable depositional conditions and a paleoenvironment characterized by a comparatively warm climate facilitated these multiple occupations at Nwya *** contemporaneous occurrence of the Upper Paleolithic blade technology on the Tibetan Plateau and most of Eurasia between 50 and 40 ka indicates rapid,large-scale dispersals of humans that profoundly affected human demography on a large *** new archaeological evidence and previously reported genetic data,we conclude that the Tibetan Plateau provided a relatively stable habitat for Upper Paleolithic hunter-gatherers,which may have contributed to the complex and multiple-origin gene pool of present-day Tibetans.

关键词： Tibetan Plateau Paleolithic Nwya Devu High-altitude adaptation Microblade industry Early Upper Paleolithic OSLdating AMS^(14)C dating

Identifying the real fracture hidden in rock microcrack zone by acoustic emission energy

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International Journal of Mining Science and Technology 2024年第6期34卷 731-746页

作者： Yuekun xing Bingxiang Huang Guangqing zhang Binghong Li Hang Xu Xuejie Jiao yang Yu Taisen Han Jinlong C{3.n state key Laboratory for Fine Exploration and Intelligent Development of Coal Resources China University of Mining and TechnologyXuzhou 221116China state key Laboratory of Petroleum Resources and Engineering China University of Petroleum-BeijingBeijing 102249China

Identifying the real fracture of rock hidden in acoustic emission(AE)source clusters(AE-depicted microcrack zone)remains challenging and *** we revealed the AE energy(representing dissipated energy)distribution rule in the rock microcrack zone and proposed an AE-energy-based method for identifying the real fracture.(1)A set of fracture experiments were performed on granite using wedgeloading,and the fracture process was detected and recorded by *** microcrack zone associated with the energy dissipation was characterized by AE sources and energy distribution,utilizing our selfdeveloped AE analysis program(RockAE).(2)The accumulated AE energy,an index representing energy dissipation,across the AE-depicted microcrack zone followed the normal distribution model(the mean and variance relate to the real fracture path and the microcrack zone width).This result implies that the nucleation and coalescence of massive cracks(i.e.,real fracture generation process)are supposed to follow a normal distribution.(3.Then,we obtained the real fracture extension path by joining the peak positions of the AE energy normal distribution curve at different cross-sections of the microcrack ***,we distinguished between the microcrack zone and the concealed real fracture within *** deviation was validated as slight as 1–3.mm.

关键词： GeoEnergy exploitation Rock fracture Fracture identification Acoustic emission AE energy analysis

A zooarchaeological study of bone assemblages from the Ma'anshan Paleolithic site

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Science china Earth sciences 2010年第3期53卷 395-402页

作者： zhang Yue1,2,3. WANG ChunXue1,2, zhang ShuangQuan1,2 & GAO xing1,2 1 {3. of Vertebrate Paleontology and Paleoanthropology, chinese academy of sciences, beijing 100044 2 Joint Laboratory of Human Evolution and Archaeometry, chinese academy of sciences, beijing 100044 3.state key Laboratory of Palaeobiology and Stratigraphy, Nanjing 210008 institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing China Joint Laboratory of Human Evolution and Archaeometry Chinese Academy of Sciences Beijing China state key Laboratory of Palaeobiology and Stratigraphy Nanjing China

Ten thousands of bone fragments were recovered from the Ma’anshan Paleolithic site, of which 43.8 pieces can be identified to skeletal elements or species. In this research, the bone assemblages are quantified based on elements of MNI, MNE, and MAU. Then bone surface modifications and skeletal element profiles of the bone assemblages are studied to understand shlepping behaviors and reveal the technique of disarticulating and defleshing the animals’ bodies, etc. Based on the analyses of bone assemblages and the comparative study with the ethnoarchaeological as well as experimental data, it is assumed that later hominids at the site made fuller use of the game animals than the earlier hominids. Incorporating the lines of evidence from chronological dating, paleoenvironment, and polished bone tools between the two cultural layers, here we propose three hypotheses suggesting that the changes of environment, the migrations of the hominids from the North, or the demographic pulses may cause such a behavioral difference. However, it is yet to be determined which hypothesis can better explain the changes.

关键词： Ma’anshan site zooarchaeology Paleolithic hominid behavior

Optimal Initialization and Starting Approach of Synchronous Condenser Integrated Power Grid

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CSEE Journal of Power and Energy Systems 2024年第1期10卷 248-260页

作者： Puyu Wang xing Liu Qingwen Mou Tao Yuan Tianming Gu hemin yang Xiao-Ping {3. Zhengrong Xiang Chunyi Guo School of Automation Nanjing University of Science and TechnologyNanjing 210094China NARI Group Corporation/state Grid EPRI and also with NARI Technology Co.Ltd. Nanjing 211106China School of Engineering University of BirminghamBirminghamB152TTUnited Kingdom state key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China

Synchronous condensers(SCs)are generally used at the receiving-end stations of ultra-high-voltage direct current(UHVDC)transmission systems due to their strong reactive power support and flexible regulation of reactive power according to the interconnected grids operating *** this paper,different starting control schemes of a SC integrated power grid are investigated providing four main contributions:1)The principle of reactive power support of the SC on the interconnected power grid is analytically studied,providing the establishment of mathematical models.2)Four different starting control schemes are developed for the initialization and SC integration,*** Scheme 1,a preset initial falling speed is directly utilized without initialization;in Scheme 2,a black start sequential control approach with a static frequency converter(SFC)is proposed;in Scheme 3.PI/PD/PID controllers are respectively applied for the excitation device at the speed-falling stage;in Scheme 4,a pre-insertion approach of an energy absorption component with R/L/RL is utilized to suppress the surges at the SC integration instant.3.The dynamic behaviors of four different starting schemes at specific operating stages are evaluated.4)The success rate of SC integration is analyzed to evaluate starting control *** of the SC interconnected system with four different starting control schemes is evaluated in the timedomain simulation environment PSCAD/EMTDC^(TM).The results prove the superiority of the proposed starting control approach in Scheme 4.

关键词： Black start dynamic behaviors excitation system pre-insertion of energy absorption components starting control schemes static frequency converter(SFC) success rate of integration synchronous condenser(SC)