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Journal of Computational Mathematics 2006年第3期24卷 281-294页

作者： Zhang-xin Chen xi-jun yu Center for Scientific Computation Box 750156 Southern Methodist University Dallas TX 75275-0156 USA Research Center for Science Xi'an Jiaotong University Xi'an 710049 China Center for Advanced Reservoir Modeling and Simulation College Vof Engineering'PekingI University China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

In this paper we consider mixed finite element methods for second order elliptic problems. In the case of the lowest order Brezzi-Douglas-Marini elements （if d = 2） or Brezzi- Douglas-Duran-Fortin elements （if d = 3） on rectangular parallelepipeds, we show that the mixed method system, by incorporating certain quadrature rules, can be written as a simple, cell-centered finite difference method. This leads to the solution of a sparse, positive semidefinite linear system for the scalar unknown. For a diagonal tensor coefficient, the sparsity pattern for the scalar unknown is a five point stencil if d = 2, and seven if d = 3. For a general tensor coefficient, it is a nine point stencil, and nineteen, respectively. Applications of the mixed method implementation as finite differences to nonisothermal multiphase, multicomponent flow in porous media are presented.

关键词： Finite difference Implementation Mixed method Error estimates Superconvergence Tensor coefficient Nonisothermal multiphase Multicomponent flow Porousmedia.

Local Discontinuous Galerkin Method for Parabolic Interface Problems

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Acta Mathematicae Applicatae Sinica 2015年第2期31卷 453-466页

作者： Zhi-juan ZHANG xi-jun yu Department of Mathematics Nanchang University Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics

In this paper, the minimal dissipation local discontinuous Galerkin method is studied to solve the parabolic interface problems in two-dimensional convex polygonal domains. The interface may be arbitrary smooth curves. The proposed method is proved to be L2 stable and the order of error estimates in the given norm is O（h｜logh｜^1/2）. Numerical experiments show the efficiency and accuracy of the method.

关键词： parabolic interface problem minimal dissipation local discontinuous Galerkin method error estimates

PRECONDITIONING HIGHER ORDER FINITE ELEMENT SYSTEMS BY ALGEBRAIC MULTIGRID METHOD OF LINEAR ELEMENTS

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Journal of Computational Mathematics 2006年第5期24卷 657-664页

作者： yun-qing Huang Shi Shu xi-jun yu Hunan Key Laboratory for Computation and Simulation in Science and Engineering Institute for Computational and Applied Mathematics Xiangtan University Xiangtan 411105 China Laboratory of Computational Physics Institute of Applied physics and Computational Mathematics Beijing 100088 China

We present and analyze a robust preconditioned conjugate gradient method for the higher order Lagrangian finite element systems of a class of elliptic problems. An auxiliary linear element stiffness matrix is chosen to be the preconditioner for higher order finite elements. Then an algebraic multigrid method of linear finite element is applied for solving the preconditioner. The optimal condition number which is independent of the mesh size is obtained. Numerical experiments confirm the efficiency of the algorithm.

关键词： Finite element Algebraic multigrid methods Preconditioned Conjugate Gradient Condition number.

Simulation study on cavity growth in ductile metal materials under dynamic loading

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Frontiers of physics 2013年第4期8卷 394-404页

作者： Ai-Guo Nu Guang-Cai Zhang Yang-jun Ying xi-jun yu National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing 100088 China

Cavity growth in ductile metal materials under dynamic loading is investigated via the material point method. Two typical cavity effects in the region subjected to rarefaction wave are identified：（i） part of material particles flow away from the cavity in comparison to the initial loading velocity, （ii） local regions show weaker negative or even positive pressures. Neighboring cavities interact via coalescence of isobaric contours. The growth of cavity under tension shows staged behaviors. After the initial slow stage, the volume and the dimensions in both the tensile and transverse directions show linear growth rate with time until the global tensile wave arrives at the upper free surface. It is interesting that the growth rate in the transverse direction is faster than that in the tensile direction. The volume growth rate linearly increases with the initial tensile velocity. After the global tensile wave passed the cavity, both the maximum particle velocity in the tensile direction and the maximum particle velocity in the opposite direction increase logarithmically with the initial tensile speed. The shock wave reflected back from the cavity and compression wave from the free surface induce the initial behavior of interracial instabilities such as the Richtmyer-Meshkov instability, which is mainly responsible for the irregularity in the morphology of deformed cavity. The local temperatures and distribution of hot spots are determined by the plastic work. Compared with the dynamical process, the heat conduction is much slower.

关键词： material point method cavity growth dynamic loading interracial instability

Lattice Boltzmann modeling and simulation of compressible flows

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Frontiers in Biology 2012年第5期7卷 582-600页

作者： Ai-Guo Xu Guang-Cai Zhang Yan-Biao Gan Feng Chen xi-jun yu National Key Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009-26Beijing 100088China North China Institute of Aerospace Engineering Langfang 065000China School of Science Linyi UniversityLinyi 276005China

In this mini-review we summarize the progress of Lattice Boltzmann （LB） modeling and simulating compressible flows in our group in recent years. Main contents include （i） Single-Relaxation-Time （SRT） LB model supplemented by additional viscosity, （ii） Multiple-Relaxation-Time （MRT） LB model, and （iii） LB study on hydrodynamic instabilities. The former two belong to improvements of physical modeling and the third belongs to simulation or application. The SRT-LB model sup- plemented by additional viscosity keeps the original framework of Lattice Bhatnagar-Gross Krook （LBGK）. So, it is easier and more convenient for previous SRT-LB users. The MRT-LB is a com- pletely new framework for physical modeling. It significantly extends the range of LB applications. The cost is longer computational time. The developed SRT-LB and MRT-LB are complementary from the sides of convenience and applicability.

关键词： lattice Boltzmann modeling compressible flows shock waves hydrodynamic instability

Mechanistic insight into the synergy between nickel single atoms and nanoparticles on N-doped carbon for electroreduction of CO2

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Journal of Energy Chemistry 2025年第1期100卷 327-336页

作者： Mingdong Sun Wenwen Guan Cailing Chen Chao Wu xiaoling Liu Biao Meng Tao Chen yu Han jun Wang Shibo xi yu Zhou State Key Laboratory of Materials-Oriented Chemical Engineering College of Chemical Engineering Nanjing Tech University Advanced Membranes and Porous Materials Center Physical Sciences and Engineering Division King Abdullah University of Science and Technology Institute of Sustainability for Chemicals Energy and Environment A*STAR (Agency for Science Technology and Research) College of Materials Science and Engineering Sichuan University

The synergy of single atoms （SAs） and nanoparticles （NPs） has demonstrated great potential in promoting the electrocatalytic carbon dioxide reduction reaction （CO2RR）;however,the rationalization of the SAs/NPs proportion remains one challenge for the catalyst ***,a Ni2+-loaded porous poly（ionic liquids）(PIL) precursor synthesized through the free radical self-polymerization of the ionic liquid monomer,1-allyl-3-vinylimidazolium chloride,was pyrolyzed to prepare the Ni,N co-doped carbon materials,in which the proportion of Ni SAs and NPs could be facilely modulated by controlling the annealing *** catalyst Ni-NC-1000 with a moderate proportion of Ni SAs and NPs exhibited high efficiency in the electrocatalytic conversion of CO2into *** Ni K-edge X-ray absorption near-edge structure （XANES） spectra and theoretical calculations were conducted to gain insight into the synergy of Ni SAs and *** charge transfer from Ni NPs to the surrounding carbon layer and then to the Ni SAs resulted in the electron-enriched Ni SAs active *** the electroreduction of CO2,the coexistence of Ni SAs and NPs strengthened the CO2activation and the affinity towards the key intermediate of*COOH,lowering the free energy for the potential-determining*CO2→*COOH step,and therefore promoted the catalysis efficiency.

关键词： Activation energy

FUBP3 mediates the amyloid-β-induced neuronal NLRP3 expression

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Neural Regeneration Research 2025年第7期20卷 2068-2083页

作者： Jing Yao yuan Li xi Liu Wenping Liang yu Li Liyong Wu Zhe Wang Weihong Song The National Clinical Research Center for Geriatric Disease Xuanwu HospitalCapital Medical UniversityBeijingChina Department of Neurology The First Affiliated Hospital of Zhengzhou UniversityZhengzhouHenan ProvinceChina Department of Neurosurgery Xuanwu HospitalCapital Medical UniversityBeijingChina Department of Pediatrics The Second Affiliated Hospital and Yuying Children’s HospitalKey Laboratory of Alzheimer’s Disease of Zhejiang ProvinceInstitute of AgingWenzhou Medical UniversityWenzhouZhejiang ProvinceChina Oujiang Laboratory(Zhejiang Laboratory for Regenerative Medicine Visionand Brain Health)WenzhouZhejiang ProvinceChina

Alzheimer's disease is characterized by deposition of amyloid-β,which forms extracellular neuritic plaques,and accumulation of hyperphosphorylated tau,which aggregates to form intraneuronal neurofibrillary tangles,in the *** NLRP3 inflammasome may play a role in the transition from amyloid-βdeposition to tau phosphorylation and *** NLRP3 is primarily found in brain microglia,and tau is predominantly located in neurons,it has been suggested that NLRP3 expressed by microglia indirectly triggers tau phosphorylation by upregulating the expression of pro-inflammatory ***,we found that neurons also express NLRP3 in vitro and in vivo,and that neuronal NLRP3 regulates tau *** biochemical methods,we mapped the minimal NLRP3 promoter and identified FUBP3 as a transcription factor regulating NLRP3 expression in *** primary neurons and the neuroblastoma cell line Neuro2A,FUBP3 is required for endogenous NLRP3 expression and tau phosphorylation only when amyloid-βis *** the brains of aged wild-type mice and a mouse model of Alzheimer's disease,FUBP3 expression was markedly increased in cortical *** analysis suggested that FUBP3 plays a role in neuron-mediated immune *** also found that FUBP3 trimmed the 5′end of DNA fragments that it bound,implying that FUBP3 functions in stress-induced *** findings suggest that neuronal NLRP3 may be more directly involved in the amyloid-β-to–phospho-tau transition than microglial NLRP3,and that amyloid-βfundamentally alters the regulatory mechanism of NLRP3 expression in *** that FUBP3 was only expressed at low levels in young wild-type mice and was strongly upregulated in the brains of aged mice and Alzheimer's disease mice,FUBP3 could be a safe therapeutic target for preventing Alzheimer's disease progression.

关键词： 5′end trimming Alzheimer's disease amyloid-beta amyloid-β-dependent transcription FUBP3 inflammasome inflammation neuron NLRP3 tau transcription factor

香菊胶囊治疗鼻窦炎的有效性和安全性的系统评价与Meta分析

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中国中药杂志 2022年第2期47卷 537-546页

作者：席俊羽吕健谢雁鸣中国中医科学院中医临床基础医学研究所北京100700 中国中医科学院西苑医院北京100091

对香菊胶囊治疗鼻窦炎的有效性和安全性进行系统评价。检索中国知网(CNKI)、万方(Wanfang)、维普(VIP)、中国生物医学文献数据库(CBM)、Cochrane Library、PubMed、EMbase、Web of Science,筛选香菊胶囊治疗鼻窦炎的随机对照试验(RCTs)... 详细信息

对香菊胶囊治疗鼻窦炎的有效性和安全性进行系统评价。检索中国知网(CNKI)、万方(Wanfang)、维普(VIP)、中国生物医学文献数据库(CBM)、Cochrane Library、PubMed、EMbase、Web of Science,筛选香菊胶囊治疗鼻窦炎的随机对照试验(RCTs),并用RevMan 5.3软件对最终纳入的研究进行Meta分析。共纳入29项研究,总样本量4331例,试验组2196例,对照组2135例。Meta分析结果显示,常规治疗+香菊胶囊的显效率(RR=1.30,95%CI[1.15,1.47],P<0.00001)、总有效率(RR=1.19,95%CI[1.16,1.23],P<0.00001)和Lund-Mackay评分(MD=-1.23,95%CI[-1.39,-1.07],P<0.00001)优于仅使用常规治疗;常规治疗+桉柠蒎肠溶软胶囊+香菊胶囊对总有效率(RR=1.14,95%CI[1.07,1.21],P<0.0001)和VAS评分的改善优于常规治疗+桉柠蒎肠溶软胶囊(MD_(头痛)=-1.29,95%CI[-1.48,-1.10],P<0.00001;MD_(鼻塞)=-1.08,95%CI[-1.21,-0.95],P<0.00001;MD_(嗅觉障碍)=-1.05,95%CI[-1.23,-0.87],P<0.00001;MD_(面部障碍)=-1.38,95%CI[-1.49,-1.27],P<0.00001);常规治疗+克拉霉素+香菊胶囊治疗鼻窦炎的总有效率(RR=1.15,95%CI[1.08,1.21],P<0.00001)优于常规治疗+克拉霉素,但对显效率(RR=1.27,95%CI[0.98,1.65],P=0.07)的改善无差异;克拉霉素+香菊胶囊对鼻窦炎患者显效率(RR=2.16,95%CI[1.47,3.18],P<0.0001)和总有效率(RR=1.48,95%CI[1.28,1.72],P<0.00001)的提高以及CT评分(MD=-1.87,95%CI[-2.01,-1.74],P<0.00001)的改善明显优于单用克拉霉素。试验序贯分析(TSA)表明,目前主要结局指标的累计样本量已经达到期望值。不良反应主要为嗜睡、腹泻和腹痛等,均与香菊胶囊无直接关系。基于现有数据和方法,香菊胶囊联合多种治疗能够提高鼻窦炎治疗的显效率和总有效率,改善CT评分、VAS评分和Lund-Mackay评分,无严重不良反应。今后仍需采用大样本、设计严谨、符合国际规范的临床试验方案来验证香菊胶囊治疗鼻窦炎的有效性与安全性。

关键词：香菊胶囊鼻窦炎系统评价 Meta分析试验序贯分析

Cross-subcarrier precoder design for massive MIMO-OFDM downlink with symplectic optimization

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Science China(Information Sciences) 2025年

作者： yu-Xuan ZHANG An-An LU xiang-Gen xiA xi-Qi GAO National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratories Department of Electrical and Computer Engineering University of Delaware

We propose a cross-subcarrier precoder design(CSPD) for massive multiple-input multiple-output(MIMO) orthogonal frequency division multiplexing(OFDM) downlink. This work aims to significantly improve the channel estimation and signal detection performance by enhancing the smoothness of the frequency domain effective channel. This is accomplished by designing a few vectors known as the transform domain precoding vectors(TDPVs), which are then transformed into the frequency domain to generate the precoders for a set of subcarriers. To combat the effect of channel aging, the TDPVs are optimized under imperfect channel state information(CSI). The optimal precoder structure is derived by maximizing an upper bound of the ergodic weighted sum-rate(WSR) and utilizing the a posteriori beam-based statistical channel model(BSCM). To avoid the large-dimensional matrix inversion, we propose an algorithm with symplectic optimization. Simulation results indicate that the proposed cross-subcarrier precoder design significantly outperforms conventional methods.

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动态矩阵控制闭环特征多项式系数的快速算法

上海交通大学学报 2003年第11期37卷 1694-1697页

作者：彭珺席裕庚上海交通大学自动化研究所上海200030

利用内模控制结构下对象至动态矩阵控制(DMC)闭环特征多项式的系数映射关系,讨论了DMC的闭环特征多项式系数的简洁表达形式.得出了DMC的闭环特征多项式系数的一种快速算法,进而得出了有关闭环系统降阶的新结果.

关键词：动态矩阵控制内模控制结构系数映射特征多项式