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Research 2024年第1期2023卷 247-259页

作者： Hao Xu Junsheng Zeng dongxiao zhang BIC-ESAT EREand SKLTCSCollege of EngineeringPeking UniversityBeijing 100871P.R.China Institute of Applied Physics and Computational Mathematics Beijing 100088P.R.China Eastern Institute for Advanced Study Eastern Institute of TechnologyNingbo 315200ZhejiangP.R.China National Center for Applied Mathematics Shenzhen(NCAMS) Southern University of Science and TechnologyShenzhen 518055GuangdongP.R.China Department of Mathematics and Theories Peng Cheng LaboratoryShenzhen 518000GuangdongP.R.China

Data-driven discovery of partial differential equations(PDEs)has recently made tremendous progress,and many canonical PDEs have been discovered successfully for proof of ***,determining the most proper PDE without prior references remains challenging in terms of practical *** this work,a physics-informed information criterion(PIC)is proposed to measure the parsimony and precision of the discovered PDE *** proposed PIC achieves satisfactory robustness to highly noisy and sparse data on 7 canonical PDEs from different physical scenes,which confirms its ability to handle difficult *** PIC is also employed to discover unrevealed macroscale governing equations from microscopic simulation data in an actual physical *** results show that the discovered macroscale PDE is precise and parsimonious and satisfies underlying symmetries,which facilitates understanding and simulation of the physical *** proposition of the PIC enables practical applications of PDE discovery in discovering unrevealed governing equations in broader physical scenes.

关键词： process canonical proof

A Comparative Study of Stochastic Collocation Methods for Flow in Spatially Correlated Random Fields

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Communications in Computational Physics 2009年第8期6卷 509-535页

作者： Haibin Chang dongxiao zhang Department of Energy and Resources Engineering College of EngineeringPeking UniversityBeijing 100871China Sonny Astani Department of Civil and Environmental Engineering University of Southern CaliforniaLos AngelesCA 90089USA

Stochastic collocation methods as a promising approach for solving stochastic partial differential equations have been developed rapidly in recent *** to Monte Carlo methods,the stochastic collocation methods are non-intrusive in that they can be implemented via repetitive execution of an existing deterministic solver without modifying *** choice of collocation points leads to a variety of stochastic collocation methods including tensor product method,Smolyak method,Stroud 2 or 3 cubature method,and adaptive Stroud *** type of collocation method,the probabilistic collocation method(PCM),has also been proposed and applied to flow in porous *** this paper,we discuss these methods in terms of their accuracy,efficiency,and applicable range for flow in spatially correlated random *** methods are compared in details under different conditions of spatial variability and correlation *** study reveals that the Smolyak method and the PCM outperform other stochastic collocation methods in terms of accuracy and *** random dimensionality in approximating input random fields plays a crucial role in the performance of the stochastic collocation *** numerical experiments indicate that the required random dimensionality increases slightly with the decrease of correlation scale and moderately from one to multiple physical dimensions.

关键词： Stochastic collocation method probabilistic collocation method stochastic partial differential equations Smolyak sparse grid method

Evaluating the uncertainty of Darcy velocity with sparse grid collocation method

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Science China(Technological Sciences) 2009年第11期52卷 3270-3278页

作者： SHI LiangSheng YANG JinZhong zhang dongxiao State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Department of Energy and Resources Engineering College of EngineeringPeking UniversityBeijing 100871China

Spatial variability of Darcy velocity is presented due to the heterogeneity of aquifer parameters. The uncertainty qualification of velocity suffers great challenge in the complex porous media. This work focuses on the use of sparse grid collocation method in velocity simulation. Since the sparse grid collocation method provides a non-intrusive way to incorporate any existing deterministic solver, the mixed finite element method is combined as the deterministic solver to retain the local continuity of Darcy velocity. We decompose the error of the velocity into three components, and illustrate that the Karhunen-Loeve truncation brings more error into velocity approximation than into head. The convergence properties of velocity moments restrict the application of sparse grid collocation method in the problems with small correlation lengths. This work provides insights towards the application of sparse grid collocation method to velocity modeling. It is demonstrated that for which problems the sparse grid collocation method is expected to be competitive with the Monte Carlo simulation. Further work about the anisotropic sparse grid collocation method should be extended to circumvent the obstacle of dimensionality.

关键词： stochastic velocity uncertainty collocation sparse grid

Physics-constrained indirect supervised learning

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Theoretical & Applied Mechanics Letters 2020年第3期10卷 155-160页

作者： Yuntian Chen dongxiao zhang Intelligent Energy Lab Frontier Research CenterPeng Cheng LaboratoryShenzhen 518000China School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhen 518055China

This study proposes a supervised learning method that does not rely on *** use variables associated with the label as indirect labels,and construct an indirect physics-constrained loss based on the physical mechanism to train the *** the training process,the model prediction is mapped to the space of value that conforms to the physical mechanism through the projection matrix,and then the model is trained based on the indirect *** final prediction result of the model conforms to the physical mechanism between indirect label and label,and also meets the constraints of the indirect *** present study also develops projection matrix normalization and prediction covariance analysis to ensure that the model can be fully ***,the effect of the physics-constrained indirect supervised learning is verified based on a well log generation problem.

关键词： Supervised learning Indirect label Physics constrained Physics informed Well logs

Two kinds of average approximation accuracy

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CAAI Transactions on Intelligence Technology 2024年第2期9卷 481-490页

作者： Qingzhao Kong Wanting Wang dongxiao zhang Wenbin zhang Department of Science Jimei UniversityXiamenChina Digital Fujian Big Data Modeling and Intelligent Computing Institute Jimei UniversityXiamenChina Department of Computer Science Michigan Technological UniversityHoughtonMichiganUSA

Rough set theory places great importance on approximation accuracy,which is used to gauge how well a rough set model describes a target ***,traditional approximation accuracy has limitations since it varies with changes in the target concept and cannot evaluate the overall descriptive ability of a rough set *** overcome this,two types of average approximation accuracy that objectively assess a rough set model’s ability to approximate all information granules is *** first is the relative average approximation accuracy,which is based on all sets in the universe and has several basic *** second is the absolute average approximation accuracy,which is based on undefinable sets and has yielded significant *** also explore the relationship between these two types of average approximation ***,the average approximation accuracy has practical applications in addressing missing attribute values in incomplete information tables.

关键词： rough sets rough set theory

F-MSAP:A practical system to detect methylation in chicken genome

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Chinese Science Bulletin 2005年第18期50卷 2039-2044页

作者： XU Qing SUN dongxiao zhang Yuan College of Animal Science and Technology China Agricultural University Beijing 100094 China

By replacing radiation with fluorescent system in the technique of methylation sensitive amplified polymor-phism (MSAP) and optimizing reaction conditions, a modi-fied technique to detect DNA methylation called F-MSAP (fluorescent labeled methylation sensitive amplified poly-morphism) was developed. In the present study, cytosine methylation patterns of genomic DNA were investigated in two inbred chickens and their F1 hybrids. Three types of methylation patterns were observed in each individual, namely fully methylated, hemi-methylated or not methylated types. The average incidence of methylation was approxi-mately 40%. The percentage that the F1 hybrid individual inherits the methylation for any given sites from either/both parent amounted to 95%, while the percentage of altered methylation patterns in F1 individual was only 5%, including 14 increased and 12 decreased methylation types, demon-strating that F-MSAP was highly efficient for large-scale detection of cytosine methylation in chicken genome. Our technique can be further extended to other animals or plants with complex genome and rich in methylation polymor-phism.

关键词：小鸡基因组多态现象 DNA 甲基化物荧光性

Adaptive Stroud Stochastic Collocation Method for Flow in Random Porous Media via Karhunen-Loeve Expansion

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Communications in Computational Physics 2008年第6期4卷 102-123页

作者： Yan Ding Tiejun Li dongxiao zhang Pingwen zhang LMAM and School of Mathematical Sciences Peking UniversityBeijing 100875P.R.China. Department of Energy and Resources Engineering College of EngineeringPeking UniversityBeijing 100871China. Department of Civil and Environmental Engineering and Mork Family Department of Chemical Engineering and Materials ScienceUniversity of Southern CaliforniaLos AngelesCA 90089USA

In this paper we develop a Stochastic Collocation Method(SCM)for flow in randomly heterogeneous porous *** first,the Karhunen-Lo`eve expansion is taken to decompose the log transformed hydraulic conductivity field,which leads to a stochastic PDE that only depends on a finite number of *** random *** on the eigenvalue decay property and a rough error estimate of Stroud cubature in SCM,we propose to subdivide the leading dimensions in the integration space for random variables to increase the *** refer to this approach as adaptive Stroud ***-and two-dimensional steady-state single phase flow examples are simulated with the new method,and comparisons are made with other stochastic methods,namely,the Monte Carlo method,the tensor product SCM,and the quasiMonte Carlo *** results indicate that the adaptive Stroud SCM is more efficient and the statistical moments of the hydraulic head can be more accurately estimated.

关键词： Adaptive Stroud stochastic collocation method Karhunen-Lo`eve expansion Monte Carlo simulation random porous flow.

Numerical Investigation of the Multiphase Flow Originating from the Muzzle of Submerged Parallel Guns

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Fluid Dynamics & Materials Processing 2023年第10期19卷 2707-2728页

作者： dongxiao zhang Lin Lu Xiaobin Qi Xuepu Yan Cisong Gao Yanxiao Hu School of Mechatronics Engineering North University of ChinaTaiyuan030051China School of Marine Science and Technology Northwestern Polytechnical UniversityXi’an710072China Northwest Institute of Mechanical Electrical Engineering Xianyang712099China

A two-dimensional model,employing a dynamic mesh technology,is used to simulate numerically the transient multiphaseﬂowﬁeld produced by two submerged parallel *** a grid reﬁnement study ensuring grid inde-pendence,ﬁve different conditions are considered to assess the evolution of cavitation occurring in proximity to the gun *** simulation results show thatﬂow interference is enabled when the distance between the par-allel barrels is relatively small;accordingly,the generation and evolution of the vapor cavity becomes more *** means of the Q criterion for vorticity detection,it is shown that cavitation causes the generation of vorticity and the evolution of the vapor cavity can result in an asymmetric distribution of vorticity for a certain distance of the *** particular,the evolution of the vapor cavity can hinder the expansion of the gas and force it toﬂow outward,while an asymmetric distribution of vorticity can lead to a gas jetﬂowing outward and rotating simultaneously.

关键词： Submerged parallel launch cavity evolution numerical simulation muzzle flow fields

Effectiveness of external Sanjierupi Gao on mastalgia caused by mammary gland hyperplasia: a placebo controlled trial

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Journal of Traditional Chinese Medicine 2013年第5期33卷 603-607页

作者： Yingyi Fan Xiaohua Pei Zhaolan Liu Zhongyuan Xia dongxiao zhang Afeng Song Duo Liu Surgical Department of the Third Hospital Affiliated to Beijing University of Traditional Chinese Medicine Centre for Evidence-based Chinese Medicine Beijing University of Chinese Medicine Surgical Department of TCM in Sino-Japanese Friendship Hospital Mammary Department of Dongfang Hospital under Beijing University of Traditional Chinese Medicine Surgical Department of the First Hospital Affiliated to Tianjin University of Traditional Chinese Medicine Surgical Department of Hubei Provincial Hospital of Traditional Chinese Medicine

OBJECTIVE:To evaluate the curative effect of external application of the Chinese drug,Sanjierupi Gao,on mastalgia caused by mammary gland ***:This randomized,double-blinded,and placebo controlled study enrolled 260 patients with mammary gland hyperplasia from five *** were randomly and equally divided in-to a Sanjierupi Gao treatment group and a placebo control *** adhesive plaster was applied to the most painful area on either breast for 7 h a *** lasted for two menstrual cycles without application during *** was used as the main index of curative *** change before and after treatment in days of mastalgia,the time to alleviate pain,pain extent,and severe pain scores were ***:Compared to the control group,the treatment group had significantly fewer days of mastalgia(P<0.01),a significantly lower severe pain score(P<0.01),and significantly less subjective pain and tenderness(P<0.05 and P<0.01,respectively).Three days before the follow-up visit,the pain score in the treatment group was significantly lower than that in the control group(P<0.05).A non-parametric test was used to compare the time to alleviate mastalgia between the two groups and found no statistical difference(Z=0.313,P=0.754).CONCLUSION:Application of Sanjierupi Gao can decrease mastalgia duration in patients with mammary gland hyperplasia during menstruation and alleviate the extent of *** time to alleviate pain is psychologically influenced.

关键词： Fibrocystic disease of breast Pain Treatment outcome Application therapy

Composite Sinusoidal Nanograting With Long-Range SERS Effect for Label-Free TNT Detection

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Photonic Sensors 2018年第3期8卷 278-288页

作者： Cheng XIAO Zhibin CHEN Mengze QIN dongxiao zhang Lei FAN Department of Electronic and Optical Engineering Shijiazhuang Campus of Army Engineering University Shijiazhuang 050003 China

A composite one-dimensional （1D） Ag sinusoidal nanograting aiming at label-free surface enhanced Raman scattering （SERS） detection of TNT with robust and reproducible enhancements is discussed. 1D periodic sinusoidal SiO2 grating followed by Ag evaporation is proposed for the creation of reproducible and effective SERS substrate based on surface plasmon polaritons （SPPs）. The optimal structure of 1D sinusoidal nanograting and its long-range SERS effect are analyzed by using the finite difference time domain （FDTD）. Simulation SERS enhancement factor （EF） can be 5 orders of magnitude as possible. This SERS substrate is prepared by the interference photolithography technology, its SERS performance is tested by Rh6G detection experiments, and the actual test EF is about 10. The label-free SERS detection capacity of TNT is demonstrated in the experiment.

关键词： Sinusoidal grating surface plasmon polaritons long-range SERS effect label-free