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Negative Index Refraction in the Complex Ginzburg-Landau Equation in Connection with the Experimental CIMA Reaction

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Chinese Physics Letters 2012年第9期29卷 110-113页

作者： yuan xu-Jin Electromagnetic Scattering Key laboratory Beijing Institute of Environmental CharacteristicsBeijing 100854

In comparison with the phenomenon of negative index refraction observed in artificial meta-materials,it is interesting to ask if this type of behavior also exists or not in reaction-diffusion systems that support nonlinear chemical *** studies indicate that the negative index refraction could occur on a interface between a medium of a normal wave and a medium that supports *** we investigate the phenomenon in the complex Ginzburg–Landau equation(CGLE)in a close relationship with the quantitative model for the chlorite-iodide-malonic acid(CIMA)*** amplitude equation CGLE is deduced from the CIMA reaction,and simulations with mapped parameters from the reaction-diffusion equation reveal that the competition between normal waves and anti-waves on the interface determines whether the negative index refraction occurs or not.

关键词： reaction. refraction Landau

Single-cell metagenomics： challenges and applications

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Protein & Cell 2018年第5期9卷 501-510页

作者： yuan xu Fangqing Zhao Computational Genomics Lab Beijing Institutes of Life Science Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China

With the development of high throughput sequencing and single-cell genomics technologies, many uncultured bacterial communities have been dissected by combining these two techniques. Especially, by simul- taneously leveraging of single-cell genomics and metagenomics, researchers can greatly improve the efficiency and accuracy of obtaining whole genome information from complex microbial communities, which not only allow us to identify microbes but also link function to species, identify subspecies variations, study host-virus interactions and etc. Here, we review recent developments and the challenges need to be addressed in single-cell metagenomics, including potential contamination, uneven sequence coverage, sequence chimera, genome assembly and annotation. With the development of sequencing and computational methods, single-cell metagenomics will undoubtedly broaden its application in various microbiome studies.

关键词： metagenomics bioinformatics single-celgenomics

ACCELERATION METHODS OF NONLINEAR ITERATION FOR NONLINEAR PARABOLIC EQUATIONS

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Journal of Computational Mathematics 2006年第3期24卷 412-424页

作者： Guang-wei yuan xu-deng Hang Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P.O.Box 8009 Beijing 100088 China

This paper discusses the accelerating of nonlinear parabolic equations. Two iterative methods for solving the implicit scheme new nonlinear iterative methods named by the implicit-explicit quasi-Newton （IEQN） method and the derivative free implicit-explicit quasi-Newton （DFIEQN） method are introduced, in which the resulting linear equations from the linearization can preserve the parabolic characteristics of the original partial differential equations. It is proved that the iterative sequence of the iteration method can converge to the solution of the implicit scheme quadratically. Moreover, compared with the Jacobian Free Newton-Krylov （JFNK） method, the DFIEQN method has some advantages, e.g., its implementation is easy, and it gives a linear algebraic system with an explicit coefficient matrix, so that the linear （inner） iteration is not restricted to the Krylov method. Computational results by the IEQN, DFIEQN, JFNK and Picard iteration methods are presented in confirmation of the theory and comparison of the performance of these methods.

关键词： Nonlinear parabolic equations Difference scheme Newton iterative methods.

Multivariate time delay analysis based local KPCA fault prognosis approach for nonlinear processes

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Chinese Journal of Chemical Engineering 2016年第10期24卷 1413-1422页

作者： yuan xu Ying Liu Qunxiong Zhu College of Information Science and Technology Beijing University of Chemical Technology

Currently, some fault prognosis technology occasionally has relatively unsatisfied performance especially for in- cipient faults in nonlinear processes duo to their large time delay and complex internal connection. To overcome this deficiency, multivariate time delay analysis is incorporated into the high sensitive local kernel principal component analysis. In this approach, mutual information estimation and Bayesian information criterion （BIC） are separately used to acquire the correlation degree and time delay of the process variables. Moreover, in order to achieve prediction, time series prediction by back propagation （BP） network is applied whose input is multivar- iate correlated time series other than the original time series. Then the multivariate time delayed series and future values obtained by time series prediction are combined to construct the input of local kernel principal component analysis （LKPCA） model for incipient fault prognosis. The new method has been exemplified in a sim- ple nonlinear process and the complicated Tennessee Eastman （TE） benchmark process. The results indicate that the new method has suoerioritv in the fault prognosis sensitivity over other traditional fault prognosis methods.

关键词： Fault prognosis Time delay estimation Local kernel principal component analysis

Squeeze flow of interstitial Herschel-Bulkley fluid between two rigid spheres

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Particuology 2010年第4期8卷 360-364页

作者： Chunhui xu Li yuan Yong xu Wenbin Hang College of Science China Agricultural University Beijing 100083 China

Interaction between two spheres with an interstitial fluid is crucial in discrete element modeling for simulating the behaviors of ＇wet＇ particulate materials. The normal viscous force of squeeze flow between two arbitrary rigid spheres with an interstitial HerscheI-Bulkley fluid was studied on the basis of Reynolds＇ lubrication theory, resulting in analytical integral expressions of pressure distribution and the viscous force between the two spheres. According to the variation of shear stress, the fluid was divided into yielding and unyielding regions, followed by a discussion on the thickness of the two regions. The result of this paper could be reduced to either the power-law fluid or the Bingham fluid case.

关键词： Wet granuleDiscrete element method Herschel-Bulldey fluid Viscous force

STEM教育赋能教育强国建设:逻辑解构、问题剖析与发展策略

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广西师范大学学报（哲学社会科学版） 2025年第1期61卷 58-71页

作者：袁磊徐济远梁世松广西师范大学教育学部广西桂林541004 广西师范大学教育区块链与智能技术教育部重点实验室广西桂林541004

教育强国政策引领下,教育、科技、人才三者的协同发展是推动国家科创资源整合、未来产业发展、加快形成新质生产力的关键。而STEM教育是能衔接三者、充分发挥三者的协同发展作用的关键一环。分析中美STEM教育相关的政策文本,发现我国STE... 详细信息

教育强国政策引领下,教育、科技、人才三者的协同发展是推动国家科创资源整合、未来产业发展、加快形成新质生产力的关键。而STEM教育是能衔接三者、充分发挥三者的协同发展作用的关键一环。分析中美STEM教育相关的政策文本,发现我国STEM教育发展存在的潜在问题有三:价值错位、功能受限、生态缺失。未来要充分发挥STEM教育对教育强国建设的赋能作用,应采取三大发展策略:明确STEM教育价值定位,构建STEM教育实践指南和建设STEM教育领域融合生态。唯有多管齐下、系统推进,我国STEM教育才能真正突破发展瓶颈,焕发勃勃生机,为培养新质人才、服务国家发展战略贡献应有力量,从而推动教育强国建设迈向新的高度。

关键词： STEM教育教育强国新质人才新质生产力中国式教育现代化

Bifurcations of Exact Traveling Wave Solutions for(2+1)-Dimensional HNLS Equation

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Communications in Theoretical Physics 2012年第1期57卷 68-70页

作者： xu yuan-Fen Junior College Zhejiang Wanli UniversityNingbo 315101China

For the(2+1)-Dimensional HNLS equation,what are the dynamical behavior of its traveling wave solutions and how do they depend on the parameters of the systems? This paper will answer these questions by using the metho... 详细信息

关键词： planar dynamical system periodic wave solution solitary wave solution (2+1)-DimensionalHNLS equation

Superconvergence Analysis of the Runge-Kutta Discontinuous Galerkin Method with Upwind-Biased Numerical Flux for Two-Dimensional Linear Hyperbolic Equation

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Communications on Applied Mathematics and Computation 2022年第1期4卷 319-352页

作者： yuan xu Qiang Zhang Department of Mathematics Nanjing UniversityNanjing 210093JiangsuChina

In this paper,we shall establish the superconvergence properties of the Runge-Kutta dis-continuous Galerkin method for solving two-dimensional linear constant hyperbolic equa-tion,where the upwind-biased numerical flux is *** suitably defining the correction function and deeply understanding the mechanisms when the spatial derivatives and the correction manipulations are carried out along the same or different directions,we obtain the superconvergence results on the node averages,the numerical fluxes,the cell averages,the solution and the spatial *** superconvergence properties in space are pre-served as the semi-discrete method,and time discretization solely produces an optimal order error in *** numerical experiments also are given.

关键词： Runge-Kutta discontinuous Galerkin method Upwind-biased flux Superconvergence analysis Hyperbolic equation Two dimensions

Hydrologic Response to Future Climate Change in the Dulong-Irra-waddy River Basin Based on Coupled Model Intercomparison Project 6

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Chinese Geographical Science 2024年第2期34卷 294-310页

作者： xu Ziyue MA Kai yuan xu HE Daming Institute of International Rivers and Eco-security Yunnan UniversityKunming 650500China Yunnan Key Laboratory of International Rivers and Transboundary Eco-security Kunming 650500China

Within the context of the Belt and Road Initiative(BRI)and the China-Myanmar Economic Corridor(CMEC),the Dulong-Ir-rawaddy(Ayeyarwady)River,an international river among China,India and Myanmar,plays a significant role as both a valuable hydro-power resource and an essential ecological ***,the water resources and security exhibit a high degree of vulnerabil-ity to climate change *** research evaluates climate impacts on the hydrology of the Dulong-Irrawaddy River Basin(DIRB)by using a physical-based hydrologic *** crafted future climate scenarios using the three latest global climate models(GCMs)from Coupled Model Intercomparison Project 6(CMIP6)under two shared socioeconomic pathways(SSP2-4.5 and SSP5-8.5)for the near(2025-2049),mid(2050-2074),and far future(2075-2099).The regional model using MIKE SHE based on historical hydrologic processes was developed to further project future streamflow,demonstrating reliable performance in streamflow simulations with a val-idation Nash-Sutcliffe Efficiency(NSE)of *** showed that climate change projections showed increases in the annual precip-itation and potential evapotranspiration(PET),with precipitation increasing by 11.3%and 26.1%,and PET increasing by 3.2%and 4.9%,respectively,by the end of the century under SSP2-4.5 and *** changes are projected to result in increased annual streamflow at all stations,notably at the basin’s outlet(Pyay station)compared to the baseline period(with an increase of 16.1%and 37.0%at the end of the 21st century under SSP2-4.5 and SSP5-8.5,respectively).Seasonal analysis for Pyay station forecasts an in-crease in dry-season streamflow by 31.3%-48.9%and 22.5%-76.3%under SSP2-4.5 and SSP5-8.5,respectively,and an increase in wet-season streamflow by 5.8%-12.6%and 2.8%-33.3%,***,the magnitude and frequency of flood events are pre-dicted to escalate,potentially impacting hydropower production and food security *** res

关键词： climate change hydrologic response Coupled Model Intercomparison Project 6(CMIP6) MIKE SHE(Système Hydrologique Europeén) Dulong-Irrawaddy River Basin