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Applying physics informed neural network for flow data assimilation

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Journal of Hydrodynamics 2020年第6期32卷 1050-1058页

作者： Xiao-dong bai yong Wang Wei Zhang Ministry of Education Key Laboratory of Coastal Disaster and Defence Hohai UniversityNanjing210098China Max Planck Institute for Dynamics and Self-Organization GöttingenGermany Science and Technology on Water Jet Propulsion Laboratory Marine and Research Institute of ChinaShanghai200011China

Data assimilation(DA)refers to methodologies which combine data and underlying governing equations to provide an estimation of a complex *** informed neural network(PINN)provides an innovative machine learning technique for solving and discovering the physics in *** encoding general nonlinear partial differential equations,which govern different physical systems such as fluid flows,to the deep neural network,PINN can be used as a tool for *** to its nature that neither numerical differential operation nor temporal and spatial discretization is needed,PINN is straightforward for implementation and getting more and more attention in the *** this paper,we apply the PINN to several flow problems and explore its potential in fluid *** the mesoscopic Boltzmann equation and the macroscopic Navier-Stokes are considered as physics *** first introduce a discrete Boltzmann equation informed neural network and evaluate it with a one-dimensional propagating wave and two-dimensional lid-driven cavity *** laminar cavity flow is also considered as an example in an incompressible Navier-Stokes equation informed neural *** parameterized Navier-Stokes,two turbulent flows,one within a C-shape duct and one passing a bump,are studied and accompanying pressure field is *** examples end with a flow passing through a porous *** in this paper show that PINN provides a new way for intelligent flow inference and identification,ranging from mesoscopic scale to macroscopic scale,and from laminar flow to turbulent flow.

关键词： Data assimilation(DA) deep learning physics informed neural network hydrodynamics

Jetting of a near-wall cavitation bubble induced by another tandem bubble

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Journal of Hydrodynamics 2024年第3期36卷 444-456页

作者： hui Han Jing-zhu Wang Jian-lin Huang Peng-bo bai yong-gang Chen Yi-wei Wang Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing100049China Guangdong Aerospace Research Academy Guangzhou511458China School of Future Technology University of Chinese Academy of SciencesBeijing100049China Jianghuai Advance Technology Center Hefei230088China

Double bubbles near a rigid wall surface collapse to produce a significant jet impact,with potential applications in surface cleaning and ultrasonic ***,the dynamic behaviors of near-wall bubbles remain *** this study,we investigate the jetting of a near-wall bubble induced by another tandem *** define two dimensionless standoff distances,γ_(1),γ_(2),to represent the distances from the center of the near-wall bubble to the rigid wall and the center of controlling bubble to the center of the near-wall bubble,*** observations reveal three distinct jetting regimes for the near-wall bubble:transferred jetting,double jetting,and directed *** further investigate the jetting mechanism,numerical simulations are conducted using the compressibleInterFoam solver in the open-source framework of OpenFOAM.A detailed analysis shows that the transferred jet flow is caused by the pinch-off resulting from the axial contraction velocity at the lower end of the near-wall bubble being greater than the vertical contraction velocity,leading to a maximum jet velocity of 682.58 m/*** the case of double jetting,intense stretching between the controlling bubble and the wall leads to a pinch-off and a double jetting with a maximum velocity of 1096.29 m/*** directed jet flow is caused by the downward movement of the high-pressure region generated by the premature collapse of the controlling bubble,with the maximum jet velocity reaching 444.62 m/s.

关键词： Jetting of near-wall bubble controlling bubble impact velocity

Effect of cooling rate on the magnetic properties of Fe_(53)Nd_(37)Al_(10) alloy

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International Journal of Minerals,Metallurgy and Materials 2013年第5期20卷 440-444页

作者： Qin bai Yan-fei Hao Jiao Wang Hua Man yong-jun Tang hui Xu Shuang Xia Key Laboratory for Microstructures Shanghai University

The effect of cooling rate on the magnetic properties of the Fe53Nd37Al10 alloy prepared by different methods, i.e., suction casting and melt spinning at different rates, was investigated. The Fe53Nd37Al10 ribbon at the wheel speed of 5 m.s-1 exhibits the highest coercivity in the samples. Two hard magnetic phases are detected from the hysteresis loops of the 5 m.s-1 ribbon at all temperatures below room temperature. Their appearance is associated with different exchange coupling interactions, which are between the two kinds of hard magnetic phases or between the hard magnetic phase and the soft magnetic phase.

关键词： amorphous materials magnetization anisotropy cooling

Mechanical properties,microstructure and surface quality of Al-1.2Mg-0.6Si-0.2Cu alloy after solution heat treatment

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Rare Metals 2017年第7期36卷 550-555页

作者： Li-Zhen Yan yong-An Zhang bai-Qing Xiong Xi-Wu Li Zhi-hui Li Hong-Wei Liu Shu-hui Huang Gang Zhao State Key Laboratory for Nonferrous Metals and Processes General Research Institute for Nonferrous Metals Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) Northeastern University

The effect of solution heat treatment （SHT） on mechanical properties, microstructure and surface quality of Al-1.2Mg-0.6Si-0.2Cu-0.6Zn alloy was investigated by tensile test, Erichsen test, surface topography, scanning electron microscope （SEM） and electron back-scattered diffraction （EBSD）. The results indicate that with the increase in SHT temperature, yield strength and cupping test value （IE） of the sheets increase greatly and reach a peak value, then decrease. Meanwhile, intermetallic com- pounds dissolve into matrix gradually. The grains grow up as SHT temperature increases, and abnormal grain growth leads to the surface defects after solution-treated above 560 ~C. Considering mechanical properties, IE value, residual phases, grain size and surface quality of the sheets, SHT temperature for the alloy should not be higher than 550 ℃.

关键词： AI-Mg-Si alloy Solution heat treatment Surface defects Mechanical properties Microstructure

Omni-Directional Distribution Patterns of Montane Coniferous Forest in the Helan Mountains of China

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Journal of Mountain Science 2013年第5期10卷 724-733页

作者： PANG Yu ZHANG bai-ping ZHAO Fang YAO yong-hui ZHANG Shuo QI Wen-wen State Key Laboratory of Resources and Environmental Information System Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of Sciences University of Chinese Academy of Sciences

Slope aspect has significant effect on the development and distribution of montane forest, especially in arid and semiarid regions. This paper, using SPOT5 images and 1：5o,ooo DEM, digitally extracts and analyzes the spatial information of montane coniferous forest （mainly Qinghai spruce）, and thereby explores how the upper and lower limits and the altitudinal range of coniferous forest vary and how the area of coniferous forest is related with annual insolation with all aspects in the Helan Mountains. The results show that： 1） In the eastern flank, the lower limit of coniferous forest is between 1,6oo m and a,ooo m a.s.l., and the upper limit between 2,800 m and 3,ooo m a.s.1.; in the western flank, the lower limit of coniferous forest is between a,ooo m and 2,300 m a.s.l., and the upper limit between 9,80o m and 3,1oo m a.s.1.2） The altitudinal ranges of coniferous forest are 8o6-1,435 m, 438-1,14o m for eastern flank and western flank, respectively. 3） The area of coniferous forest takes on a normal distribution with aspect, and it has a close relationship with annual insolation. This distribution model developed in this paper quantitatively reveals the significant effect of slope aspect on the distribution of coniferous forest in arid and semi-arid land.

关键词： Arid region Helan Mountains Qinghaispruce (Picea crassifolia) Aspect effect Coniferousforest Normal distribution

Kernel Estimators of the ROC Curve with Censored Data

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Acta Mathematicae Applicatae Sinica 2013年第1期29卷 43-54页

作者： Fang-fang bai yong Zhou Academy of Mathematics and Systems Science Chinese Academy of Sciences School of Statistics and Management Shanghai University of Finance and Economics

Receiver operating characteristic （ROC） curves are often used to study the two sample problem in medical studies. However, most data in medical studies are censored. Usually a natural estimator is based on the Kaplan-Meier estimator. In this paper we propose a smoothed estimator based on kernel techniques for the ROC curve with censored data. The large sample properties of the smoothed estimator are established. Moreover, deficiency is considered in order to compare the proposed smoothed estimator of the ROC curve with the empirical one based on Kaplan-Meier estimator. It is shown that the smoothed estimator outperforms the direct empirical estimator based on the Kaplan-Meier estimator under the criterion of deficiency. A simulation study is also conducted and a real data is analyzed.

关键词： ROC curve smoothed estimator censored data Kaplan-Meier estimator deficiency

Cognitive behavioral therapy on personality characteristics of cancer patients

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World Journal of Clinical Cases 2021年第31期9卷 9386-9394页

作者： Xiao-hui Yuan Juan Peng Shu-Wei Hu yong Yang Yu-Ju bai Zunyi Medical University Zunyi 563000Guizhou ProvinceChina Teaching and Research Office of Medical Psychology Zunyi Medical UniversityZunyi 563003Guizhou ProvinceChina Department of Oncology Affiliated Hospital of Zunyi Medical UniversityZunyi 563000Guizhou ProvinceChina

BACKGROUND The main treatment methods for cancer include surgery,radiotherapy,chemotherapy,targeted drug therapy and so *** often feel anger,anxiety,depression,and other negative psychological reactions in the process of *** To explore the effects of cognitive behavioral therapy on the personality characteristics of cancer *** According to the matching design requirements,150 cancer patients were divided into 3 groups based on sex,age,condition,and cultural *** in the control group received conventional *** in experimental group 1 received an intervention based on conventional treatment combined with cognitive behavioral *** in experimental group 2 received family members'participation in addition to the treatment given in experimental group *** Eysenck personality questionnaire was used to investigate all the patients before and after the intervention,and the scores for psychosis,introversion,neuroticism,and concealment degree were *** Compared with the control group,for experimental group 1 and experimental group 2 before and after the intervention,the four dimensions of mental quality,neuroticism,introversion and concealment degree all decreased,and the difference was statistically significant(P0.05)among the control group,experimental group 1,and experimental group 2 for two personality traits,psychoticism and neuroticism,both inside and outside degree and all four *** Simple cognitive behavioral therapy could not change the personality characteristics of cancer patients quickly,but the patients’personality characteristics were significantly improved after treatment.

关键词： Cognitive behavioral therapy Cancer patients Personality characteristics Psychosis Introversion Neuroticism Degree of validity

Quench sensitivity of Al-Cu-Mg alloy thick plate

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Rare Metals 2023年第9期42卷 3161-3169页

作者： Yuan Yin Bing-hui Luo Zhen-Hai bai hui-Bo Jing School of Materials Science and Engineering Central South UniversityChangsha410083China

The quench sensitivity of Al-Cu-Mg alloy was investigated at different thicknesses of the thick *** quenching process was simulated via finite element analysis(FEA);time-temperature-property(TTP)curves and time-temperature-transformation(TTT)curves were obtained through hardness test and differential scanning calorimetry(DSC)test;and the microstructural observation was carried out by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Experimental results exhibit that the quench cooling rate decreases dramatically from the surface to the center of the plate,and the inhomogeneous quenching causes the difference in *** the decrease in quench cooling rate,constituent particles are coarsening gradually;the quantity of T-phase(Al_(20)Cu_(2)Mn_(3))increases and the S-phase(Al_(2)Cu Mg)*** to the precipitation kinetics analysis,the decrease in S-phase is caused by the increase in precipitate activation *** that the center of the plate shows the highest quenching sensitivity,which is consistent with the analysis of time-temperature-property curves and time-temperature-transformation curves.

关键词： Al-Cu-Mg alloy Quench sensitivity Precipitation kinetics Time-temperature-property curves Microstructure

Stereoselective Ring-opening Polymerization of rac-Lactide by Bulky Chiral and Achiral N-heterocyclic Carbenes

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Chinese Journal of Polymer Science 2018年第2期36卷 231-236页

作者： hui Li bai-Ru Ai Miao Hong Key Laboratory of Marine Materials and Related Technologies Key Laboratory of Marine Materials and Protective Technologies of Zhejiang Province Ningbo Institute of Materials Technology and EngineeringChinese Academy of SciencesNingbo 315201China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Organometallic Chemistry Shanghai Institute of Organic ChemistryChinese Academy of SciencesShanghai 200032China

Despite the extraordinary success has been achieved in metal catalyst-promoted stereoselective ring-opening polymerization（ROP） of rac-lactide（rac-LA）, well-controlled stereoselective rac-LA ROP by organic catalyst still remains a scientific challenge. Here we report our investigations into organocatalytic stereoselective ROP of rac-LA by utilizing novel bulky chiral and achiral N-heterocyclic carbenes（NHC）, 1,3-bis-（1′-naphthylethyl）imidazolin-2-ylidene. The effect of polymerization conditions（e.g. solvent, temperature, alcohol initiator） on ROP behavior by these bulky NHCs has been fully studied, leading to the formation of isotactic-rich stereoblock polylactide（Pi = 0.81） under optimized conditions with high activity（Conv. = 98% in 30 min） and narrow molecular weight dispersity（D = 1.05）.

关键词： Polylactide Ring-opening polymerization Stereoselectivity Organic catalyst N-heterocyclic carbene