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FINITE ELEMENT APPROXIMATIONS OF SYMMETRIC TENSORS ON SIMPLICIAL GRIDS IN R^n： THE HIGHER ORDER CASE

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Journal of Computational Mathematics 2015年第3期33卷 283-296页

作者： Jun Hu LMAM School of Mathematical Sciences and Beijing International Center for Mathematical Research Peking University Beijing 100871 P. R. China.

The design of mixed finite element methods in linear elasticity with symmetric stress approximations has been a longstanding open problem until Arnold and Winther designed the first family of mixed finite elements where the discrete stress space is the space of H（div,Ω;S）-Pk＋1 tensors whose divergence is a Pk-1 polynomial on each triangle for k ≥ 2. Such a two dimensional family was extended, by Arnold, Awanou and Winther, to a three dimensional family of mixed elements where the discrete stress space is the space of H（div, Ω; S）-Pk＋2 tensors, whose divergence is a Pk-1 polynomial on each tetrahedron for k ≥ 2. In this paper, we are able to construct, in a unified fashion, mixed finite element methods with symmetric stress approximations on an arbitrary simplex in R^n for any space dimension. On the contrary, the discrete stress space here is the space of H（div,Ω; S）-Pk tensors, and the discrete displacement space here is the space of L^2（Ω; R^n）-Pk＋1 vectors for k ≥ n＋ 1. These finite element spaces are defined with respect to an arbitrary simplicial triangulation of the domain, and can be regarded as extensions to any dimension of those in two and three dimensions by Hu and Zhang.

关键词： Mixed finite element Symmetric finite element First order system Simplicial grid Inf-sup condition.

A typical Riedel Shear Pattern of active faults in the Laolongwan Basin， Northeastern Tibetan Plateau

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Journal of Earth Science 2024年

作者： Kai-Xun WANG Xiao-Gang LI Wei SHI Xiang-You FENG Qian YANG Jie LI Zheng-Jian XU Zhou-Jun PENG Shao-Hua XU Yi-Xue XIONG Mao LIN School of Petroleum Engineering， Chongqing University of Science and Technology Chongqing Key Laboratory of Complex Oil and Gas Field Exploration and Development， Chongqing University of Science and Technology Geophysics research Institute of Jiangsu Oilfield Company，SINOPEC SinoProbe Laboratory， Chinese Academy of Geological Sciences Academy of Dazu Rock Carvings

Riedel shear system， consists of some different oriented faults and derivative structures， is an important pattern of tectonic activity and stress regulation， which has been widely applied to the interpretation of intracontinental deformation. The Laolongwan Basin， located in the western Haiyuan fault zone at the northeastern Tibetan Plateau， is a key area to study the Cenozoic intracontinental deformation in the northeastern plateau， which formed a complex active fault system during the Cenozoic. However， the activity of these faults and their kinematic mechanism remain unclear. In this contribution， based on detailed structural interpretation of remote sensing image， field observations and OSL dating analysis， we propose a Riedel Shear model of active fault system in the Laolongwan basin. Our observations show that this active fault system is consist of four major faults， including the left strike-slip Hasi Shan Fault and Zihong Shan Fault with thrusting characteristics， the Southern Zihong Shan thrust fault and the Mijia Shan normal fault. The fault offset and OSL dating analyses suggest that the left-lateral slip rate of the Hasi Shan Fault is ～ 2.60-3.01 mm/a since ca. 15 ka， whereas the Zihong Shan Fault is ～ 1.10-1.13 mm/a since ca. 14 ka. Fault-slip vectors analyses indicate that the active fault system related to the Riedel Shear in the Laolongwan Basin was controlled by the regional ENE-WSW compressive stress. This compression also caused the significant left-lateral strike-slip movement along the Haiyuan Fault zone at the same time， which might result from the northeastward continuous expanding of the Tibetan Plateau during the late Cenozoic.

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Symmetry-Dependent Kinetics of Dislocation Reaction

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Chinese Physics Letters 2021年第6期38卷 45-48页

作者： Hong Yu Chen Lei Wang Tian Hui Zhang center for Soft Condensed Matter Physics and Interdisciplinary research Soochow UniversitySuzhou 215006China School of Physical Science and Technology Soochow UniversitySuzhou 215006China

Reactions between dislocations are investigated in two-dimensional colloidal *** is found that,because of the conservation of total Burgers vectors,the kinetics of the reaction is dependent on the the symmetry of the crystal *** is possible only when the total Burgers vector of the reacting dislocations is in line with existing crystal *** non-merging reactions,the number of dislocations cannot be reduced but the interacting dislocations can exchange their Burgers vectors and migrate to different gliding *** changing of gliding lines promises additional annihilation in multi-dislocation *** bonding of non-merging dislocations determines the configuration and the orientation of the grain *** findings in this study may shed new light on understanding of dislocations and have potential applications in fabrication of crystalline materials.

关键词： grain Kinetics annihilation

RPL1, a Gene Involved in Epigenetic Processes Regulates Phenotypic Plasticity in Rice

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Molecular Plant 2012年第2期5卷 482-493页

作者： Cui-Cui Zhang Wen-Ya Yuan Qi-Fa Zhang National Key Laboratory of Crop Genetic Improvement National Center of Plant Gene ResearchHuazhong Agricultural UniversityWuhan 430070China

Organisms can adjust their phenotype in response to changing environmental conditions. This phenomenon is termed phenotypic plasticity. Despite its ubiquitous occurrence, there has been very little study on the molecular mechanism of phenotypic plasticity. In this study, we isolated a rice （Oryza sativa L.） mutant, rice plasticity 1 （rpl1）, that displayed increased environment-dependent phenotypic variations. RPL1 was expressed in all tissues examined. The protein was localized in the nucleus and its distribution in the nucleus overlapped with heterochromatin. The rpll mutation led to an increase in DNA methylation on repetitive sequences and a decrease in overall histone acetylation. In addition, the mutation affected responses of the rice plant to phytohormones such as brassinosteroid, gibberellin, and cytokinin. Analysis of the putative rice brassinosteroid receptor OsBRI1, a key hormone signaling gene, indicated that RPL1 may be involved in the regulation of epigenomic modification of the gene. These data suggest that RPL1 regulated phenotypic plasticity likely through its involvement in epigenetic processes affecting responses of the plant to phytohormones.

关键词： Phenotypic plasticity RPL1 epigenetics phytohormone evolution.

Integrated and dual-responsive lipopeptide nanovector with parallel effect to tumor and micro-environment regulation by efficient gene and drug co-delivery

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Chinese Chemical Letters 2023年第5期34卷 420-426页

作者： Xiaobing Chen Huan Yang Xu Song Hong Liang Yu Wei Jiao Lu Matthias Barz Rongrong Jin Yu Nie National Engineering research center for Biomaterials Sichuan UniversityChengdu 610064China Leiden Academic center for Drug research(LACDR) Leiden UniversityLeiden 2333 CCThe Netherlands Department of Pharmacy Sichuan Academy of Medical Sciences&Sichuan Provincial People's HospitalSchool of MedicineUniversity of Electronic Science and Technology of ChinaChengdu 610072China

The integrated lipopeptide(RVA)/gene complexes are fabricated with bi-directional regulation on tumor cells and *** self-assembling and target coating modification,the poly(γ-glutamic acid)(γ-PGA)/RVA nano-vectors can sequentially respond to pH&redox stimuli,and guarantee efficient therapeutic gene delivery and control release of all-trans retinoic *** design provides a facile but promising strategy to treat refractory cancers.

关键词： Gene delivery Integrated co-delivery Dual-responsive Lipopeptide Tumor micro-environment regulation

Diagnostic analysis of mesoscale rainstorms in the Jiang-Huai valley of China with convective vorticity vector

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Progress in Natural Science:Materials International 2007年第5期17卷 559-568页

作者： Cui Xiaopeng, Gao Shouting and Li Xiaofan (Laboratory of Cloud-Precipitation Physics and Severe Storms (LACS), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China Joint center for Satellite Data Assimilation and NOAA/NESDIS/center for Satellite Applications and research, Camp Springs, Maryland, USA) Laboratory of Cloud-Precipitation Physics and Severe Storms (LACS) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Joint center for Satellite Data Assimilation and NOAA/NESDIS/center for Satellite Applications and research Camp Springs Maryland USA

By the vector product of absolute vorticity vectors and equivalent potential temperature gradients, a new vector, convec-tive vorticity vector (CVV) is readdressed after Gao et al., and is applied to the study of the development and movement of mesoscale rainstorms in the Jiang-Huai valley of China by using high-resolution simulation data with PSU/NCAR MM5 briefly. The results show that the CVV, especially its vertical component which is closely related to interactions between vertical secondary circulations and horizontal equivalent potential temperature gradients, may be a good tracer and diagnostic tool in the study of mesoscale rainstorms in the Jiang-Huai valley of China. And the main physical processes responsible for the variations of the vertical component of the CVV are discussed briefly based on its tendency equation proposed in this article.

关键词： convective vorticity vector mesoscale rainstorms tendency equations.

An orthogonally accumulated projection method for symmetric linear system of equations

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Science China Mathematics 2016年第7期59卷 1235-1248页

作者： PENG Wu Jian LIN Qun ZHANG Shu Hua Department of Mathematics and Statistics Zhaoqing University Academy of Mathematics and Systems Science Chinese Academy of Sciences research center for Mathematics and Economics Tianjin University of Finance and Economics

A direct as well as iterative method(called the orthogonally accumulated projection method, or the OAP for short) for solving linear system of equations with symmetric coefficient matrix is introduced in this paper. With the Lanczos process the OAP creates a sequence of mutually orthogonal vectors, on the basis of which the projections of the unknown vectors are easily obtained, and thus the approximations to the unknown vectors can be simply constructed by a combination of these projections. This method is an application of the accumulated projection technique proposed recently by the authors of this paper, and can be regarded as a match of conjugate gradient method(CG) in its nature since both the CG and the OAP can be regarded as iterative methods, too. Unlike the CG method which can be only used to solve linear systems with symmetric positive definite coefficient matrices, the OAP can be used to handle systems with indefinite symmetric matrices. Unlike classical Krylov subspace methods which usually ignore the issue of loss of orthogonality, OAP uses an effective approach to detect the loss of orthogonality and a restart strategy is used to handle the loss of *** experiments are presented to demonstrate the efficiency of the OAP.

关键词： iterative method accumulated projection conjugate gradient method Krylov subspace

Symmetry selective directionality in near-field acoustics

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National Science Review 2020年第6期7卷 1024-1035页

作者： Yang Long Hao Ge Danmei Zhang Xiangyuan Xu Jie Ren Ming-Hui Lu Ming Bao Hong Chen Yan-Feng Chen center for Phononics and Thermal Energy Science China-EU Joint Center for Nanophononics Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Sciences and Engineering Tongji University Department of Materials Science and Engineering College of Engineering and Applied Sciences and National Laboratory of Solid State Microstructures Nanjing University Key Laboratory of Noise and Vibration research Institute of Acoustics Chinese Academy of Sciences Collaborative Innovation center of Advanced Microstructures Nanjing University Key Laboratory of Noise and Vibration research Institute of Acoustics Chinese Academy of Sciences Beijing 100190 China and4Collaborative Innovation Center of Advanced Microstructures Nanjing University

Understanding unidirectional and topological wave phenomena requires the unveiling of intrinsic geometry and symmetry for wave dynamics. This is essential yet challenging for the flexible control of near-field evanescent waves, highly desirable in broad practical scenarios ranging from information communication to energy radiation. However, exploitations of near-field waves are limited by a lack of fundamental understanding about inherent near-field symmetry and directional coupling at sub-wavelengths, especially for longitudinal waves. Here, based on the acoustic wave platform, we show the efficient selective couplings enabled by near-field symmetry properties. Based on the inherent symmetry properties of three geometrically orthogonal vectors in near-field acoustics, we successfully realize acoustic Janus, Huygens,spin sources and quadrupole hybrid sources, respectively. Moreover, we experimentally demonstrate fertile symmetry selective directionality of those evanescent modes, supported by two opposite meta-surfaces. The symmetry properties of the near-field acoustic spin angular momenta are revealed by directly measuring local vectorial fields. Our findings advance the understanding of symmetries in near-field physics, supply feasible approaches for directional couplings, and pave the way for promising acoustic devices in the future.

关键词： acoustics near field symmetry

Numerical simulation of dynamic process ofthe Tangshan earthquake

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Acta Seismologica Sinica(English Edition) 1999年第5期12卷 516-524页

作者：蔡永恩何涛王仁 Geodynamic research center Department of Geophysics Peking University Beijing China Department of Geology Peking University Beijing China

In this paper. :LDDA (Lagrangian Discontinuous Deformation Analysis) method is used in modeling thedynamic process of the M,=7.8 Tang shan earthquake on July 28, 1976 and obtain directly the dynamic and quasi static dislocations. shear stress drops, fracture velocities of the Tang shan earthquake fault. The simulation showsthai the slip history at each point of the fault is different. The displacement vectors at the concave side of the faultis greater than that of the convex side of the fault. The 'over shoot' of the fault slip is greatest at the middle part ofthe fault and attenuates to its ends. The rupture velocities of the fault from the epicenter towards south-west andtowards north-east are 3.08 m/s and 1. 18 m/s, respectively, the average one is 2.13 In/s. The maximum dynamic.m quasi-static dislocations are 7. 1 m and 6.2 m respectively. the average quasi-static one on the fault is 4.5 *** stress dynamic and quasi-static shear stress drops are 8.1 M Pa and 5.4 MP4 respectively, the averagequasi-static shear stress drop is 3.9 M Pa. We found that the rupture velocities and shear stress are related to theinitial stress states of the fault.

关键词： rupture of multi-elastic body system discontinuous deformation dynamic analysis method Tangshan earthquake numerical simulation