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Development of quadrilateral spline thin plate elements using the B-net method

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Acta Mechanica Sinica 2013年第4期29卷 567-574页

作者： Juan Chen chong-jun li School of Mathematics and Quantitative Economics Dongbei University of Finance and Economics School of Mathematical Sciences Dalian University of Technology

The quadrilateral discrete Kirchhoff thin plate bending element DKQ is based on the isoparametric element Q8, however, the accuracy of the isoparametric quadrilateral elements will drop significantly due to mesh distortions. In a previous work, we constructed an 8-node quadrilateral spline element L8 using the triangular area coordinates and the B- net method, which can be insensitive to mesh distortions and possess the second order completeness in the Cartesian co- ordinates. In this paper, a thin plate spline element is devel- oped based on the spline element L8 and the refined tech- nique. Numerical examples show that the present element indeed possesses higher accuracy than the DKQ element for distorted meshes.

关键词： Spline finite element ~ Refined quadrilateral el-ement ~ Discrete Kirchhoff plate element ~ Triangular areacoordinates ~ B-net method

A 3D pyramid spline element

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Acta Mechanica Sinica 2011年第6期27卷 986-993页

作者： Juan Chen chong-jun li Wan-Ji Chen School of Mathematics and Quantitative Economics Dongbei University of Finance and Economics 116025 Dalian China School of Mathematical Sciences Dalian University of Technology116024 Dalian China Key Laboratory of liaoning Province for Composite Structural Analysis of Aerocraft and Simulation Shenyang Aerospace University 110136 Shenyang China State Key Laboratory for Structural Analysis of Industrial Equipment Dalian University of Technology 116024 Dalian China

In this paper,a 13-node pyramid spline element is derived by using the tetrahedron volume coordinates and the B-net method,which achieves the second order completeness in Cartesian *** appropriate examples were employed to evaluate the performance of the proposed *** numerical results show that the spline element has much better performance compared with the isoparametric serendipity element Q20 and its degenerate pyramid element P13 especially when mesh is distorted,and it is comparable to the Lagrange element *** has been demonstrated that the spline finite element method is an efficient tool for developing high accuracy elements.

关键词： Spline finite element Pyramid element The second order completeness B-net method

Construction of n-sided polygonal spline element using area coordinates and B-net method

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Acta Mechanica Sinica 2010年第5期26卷 685-693页

作者： Juan Chen chong-jun li Wan-Ji Chen School of Mathematical Sciences Dalian University of Technology 116024 Dalian China State Key Laboratory for Structural Analysisof Industrial Equipment Dalian University of Technology116024 Dalian China Institute for Structural Analysis of Aerocraft Shenyang Institute of Aeronautical Engineering110136 Shenyang China

In general, triangular and quadrilateral elements are commonly applied in two-dimensional finite element methods. If they are used to compute polycrystalline materials, the cost of computation can be quite significant. Polygonal elements can do well in simulation of the materials behavior and provide greater flexibility for the meshing of complex geometries. Hence, the study on the polygonal element is a very useful and necessary part in the finite element method. In this paper, an n-sided polygonal element based on quadratic spline interpolant, denoted by PS2 element, is presented using the triangular area coordinates and the B-net method. The PS2 element is conforming and can exactly model the quadratic field. It is valid for both convex and non-convex polygonal element, and insensitive to mesh distortions. In addition, no mapping or coordinate transformation is required and thus no Jacobian matrix and its inverse are evaluated. Some appropriate examples are employed to evaluate the performance of the proposed element.

关键词： Finite element method n-sided polygonalelement - Bivariate spline interpolation The second ordercompleteness

ON THE PROBLEM OF INSTABIliTY IN THE DIMENSIONS OF SPliNE SPACES OVER T-MESHES WITH T-CYCLES

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Journal of Computational Mathematics 2015年第3期33卷 248-262页

作者： Qing-Jie Guo Ren-Hong Wang chong-jun li School of Mathematical Sciences Dalian University of Technology Dalian 116024 China

The T-meshes are local modification of rectangular meshes which allow T-junctions. The splines over T-meshes are involved in many fields, such as finite element methods, CAGD etc. The dimension of a spline space is a basic problem for the theories and applications of splines. However, the problem of determining the dimension of a spline space is difficult since it heavily depends on the geometric properties of the partition. In many cases, the dimension is unstable. In this paper, we study the instability in the dimensions of spline spaces over T-meshes by using the smoothing cofactor-conformality method. The modified dimension formulas of spline spaces over T-meshes with T-cycles are also presented. Moreover, some examples are given to illustrate the instability in the dimensions of the spline spaces over some special meshes.

关键词： Spline space Smoothing cofactor-conformality method Instability in the dimension T-meshes.

A Distributed Cooperative Dynamic Task Planning Algorithm for Multiple Satellites Based on Multi-agent Hybrid Learning

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Chinese Journal of Aeronautics 2011年第4期24卷 493-505页

作者： WANG chong li jun JING Ning WANG jun CHEN Hao College of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China

Traditionally, heuristic re-planning algorithms are used to tackle the problem of dynamic task planning for multiple satellites. However, the traditional heuristic strategies depend on the concrete tasks, which often affect the result’s optimality. Noticing that the historical information of cooperative task planning will impact the latter planning results, we propose a hybrid learning algorithm for dynamic multi-satellite task planning, which is based on the multi-agent reinforcement learning of policy iteration and the transfer learning. The reinforcement learning strategy of each satellite is described with neural networks. The policy neural network individuals with the best topological structure and weights are found by applying co-evolutionary search iteratively. To avoid the failure of the historical learning caused by the randomly occurring observation requests, a novel approach is proposed to balance the quality and efficiency of the task planning, which converts the historical learning strategy to the current initial learning strategy by applying the transfer learning algorithm. The simulations and analysis show the feasibility and adaptability of the proposed approach especially for the situation with randomly occurring observation requests.

关键词： multiple satellites dynamic task planning problem multi-agent systems reinforcement learning neuroevolution of augmenting topologies transfer learning

复杂地壳接收函数H-κ叠加——以安纳托利亚板块为例

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地球物理学报 2016年第11期59卷 4048-4062页

作者：危自根储日升陈凌崇加军李志伟中国科学院测量与地球物理研究所大地测量与地球动力学国家重点实验室武汉430077 中国科学院地质与地球物理研究所岩石圈演化国家重点实验室北京100029 中国科学院青藏高原地球科学卓越创新中心北京100101

本文理论分析了具有不同沉积层和壳幔过渡带结构的接收函数及其相关的H-κ叠加结果,然后采用接收函数H-κ叠加和波形反演方法获得了具有复杂构造演化历史的中北安纳托利亚板块的地壳厚度(H)、V_P/V_S(κ)和V_S结构.理论分析表明:厚的沉... 详细信息

本文理论分析了具有不同沉积层和壳幔过渡带结构的接收函数及其相关的H-κ叠加结果,然后采用接收函数H-κ叠加和波形反演方法获得了具有复杂构造演化历史的中北安纳托利亚板块的地壳厚度(H)、V_P/V_S(κ)和V_S结构.理论分析表明:厚的沉积层或沉积层和厚的壳幔过渡带共存都会使H-κ叠加失效;渐变型壳幔过渡带导致H-κ叠加的H位于过渡带中间,且随着频率增大逐渐靠近过渡带上方;倒转型壳幔过渡带导致H-κ叠加具有多极值,其结果可能反应过渡带内最大波阻抗界面上的地壳结构;1km·s^(-1)的V_P变化会导致H-κ叠加的H变化7km,而κ变化较小.实际资料分析表明:中北安纳托利亚H,κ和V_S具有强烈的横向不均匀性,大部分区域沉积层厚度3km;北安纳托利亚断层切穿地壳,在局部地区可能存在流体;研究区存在残留古老的小陆块体.本文研究表明,仔细分析接收函数波形和其随方位角的变化特征且用其他地震学方法进行约束,有助于采用H-κ叠加方法获取复杂地壳结构信息.

关键词：接收函数H-κ叠加波形反演沉积层壳幔过渡带安纳托利亚板块

Multiphase reaction spinning of high-temperature resistant weavable SiO_(2)-Kevlar hybrid aerogel fibers

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Nano Research 2025年第1期18卷 424-433页

作者： Yunna Chen Wenlu Zhang Qingyang li Wenbin li chong He School of Textile Science and Engineering Wuhan Textile UniversityWuhan 430200China State Key Laboratory of New Textile Materials and Advanced Processing Technologies Wuhan Textile UniversityWuhan 430200China

Advanced aerogel fibers possess numerousadvantages amalgamating the attributes of aerogels and fibermaterials, rendering them invaluable in the realm of thermalmanagement and regulation. However, the achievement ofrobust mechanical properties and increased temperaturestability is still a major challenge for the majority of aerogelfibers. Herein, SiO_(2)-Kevlar hybrid aerogel fibers with bioniccore-shell structure were prepared by reaction spinning andweaved into fabric. Kevlar nanowires dispersion is pumpedinto a bath comprising a self-synthesized silica sol, whichfacilitates the hybridization of biphasic aerogels through thegel reaction. Precise control over the diameter (200-800 μm)and structure of the wet gel fibers was achieved throughmeticulous adjustment of the spinning solution composition and spinning parameters. Subsequent freeze-drying processfacilitates the formation of a core-shell hybrid structure, in which the SiO_(2) aerogel layer effectively encapsulate the Kevlaraerogel core fiber. Taking full advantage of the mechanical properties of the Kevlar core fiber, the resulting SiO_(2)-Kevlaraerogel fibers exhibit commendable weaving characteristics (51.8 MPa). Furthermore, SiO_(2)-Kevlar aerogel fabrics exhibitenhanced thermal insulation characteristics with a thermal conductivity of 0.037 W/(m·K). As a result of the presence ofexternal SiO_(2) aerogel layer, the overall temperature resistance performance of the SiO_(2)-Kevlar fabric reach up to 700 ℃.

关键词： aerogel fibers SiO_(2)aerogel Kevlar aerogel reaction spinning thermal protective performance

Targeting cholesterol trafficking to mitigate axonal degeneration in hereditary spastic paraplegia

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Neural Regeneration Research 2025年第5期20卷 1397-1398页

作者： Zhenyu Chen Xue-jun li Department of Biomedical Sciences University of Illinois College of Medicine RockfordRockfordILUSA Department of Bioengineering University of Illinois at ChicagoChicagoILUSA

Axonal degeneration underlies many debilitating diseases including hereditary spastic paraplegia(HSP),a genetically and clinically diverse group of disorders characterized by spasticity and weakness of the lower *** is one significant cause of chronic neurodisability due to the lack of effective treatments and a wide range of onset ages from early childhood to 70 years.

关键词： degeneration diseases hereditary

Molecular mechanism and functional research of GAPDH S-nitrosylation induced by cerebral ischemia-reperfusion

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Molecular mechanism and functional research of GAPDH S-nitro...