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Development of a Three-Dimensional Multiscale Octree SBFEM for Viscoelastic Problems of Heterogeneous Materials

Computer Modeling in Engineering & Sciences 2024年第8期140卷 1831-1861页

作者： Xu Xu Xiaoteng Wang Haitian yang zhenjun yang Yiqian He State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDepartment of Engineering MechanicsDalian University of TechnologyDalian116024China Hubei Key Laboratory of Geotechnical and Structural Safety School of Civil EngineeringWuhan UniversityWuhan430072China Mechanik–Materialtheorie Ruhr-Universität BochumBochum44801Germany

The multiscale method provides an effective approach for the numerical analysis of heterogeneous viscoelastic materials by reducing the degree of freedoms(DOFs).A basic framework of the Multiscale Scaled Boundary Finite Element Method(MsSBFEM)was presented in our previous works,but those works only addressed two-dimensional *** order to solve more realistic problems,a three-dimensional MsSBFEM is further developed in this *** the proposed method,the octree SBFEM is used to deal with the three-dimensional calculation for numerical base functions to bridge small and large scales,the three-dimensional image-based analysis can be conveniently conducted in small-scale and coarse nodes can be flexibly adjusted to improve the computational ***,the Temporally Piecewise Adaptive Algorithm(TPAA)is used to maintain the computational accuracy of multiscale analysis by adaptive calculation in time *** results of numerical examples show that the proposed method can significantly reduce the DOFs for three-dimensional viscoelastic analysis with good *** instance,the DOFs can be reduced by 9021 times compared with Direct Numerical Simulation(DNS)with an average error of 1.87%in the third example,and it is very effective in dealing with three-dimensional complex microstructures directly based on images without any geometric modelling process.

关键词： Three-dimensionalmultiscale viscoelastic analysis numerical base functions octree SBFEM image-based analysis temporally piecewise adaptive algorithm

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基于CT图像深度学习的三维编织C/C复合材料微观组分与缺陷智能识别

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复合材料学报 2024年第7期41卷 3536-3543页

作者：钱奇伟张昕杨贞军沈镇校金友武汉大学土木建筑工程学院武汉430072 浙江大学建筑工程学院杭州310058 西安航天复合材料研究所西安710025 西北工业大学航天学院西安710072

首先采用微观X射线计算机断层扫描(Micro X-ray computed tomography,XCT)对4枚20 mm立方体三维编织碳/碳(Carbon fiber reinforced carbon,C/C)复合材料试件进行扫描,获得精度为18.27μm的内部微观结构图像;然后采用基于深度学习的语... 详细信息

首先采用微观X射线计算机断层扫描(Micro X-ray computed tomography,XCT)对4枚20 mm立方体三维编织碳/碳(Carbon fiber reinforced carbon,C/C)复合材料试件进行扫描,获得精度为18.27μm的内部微观结构图像;然后采用基于深度学习的语义分割算法,对大量二维XCT图像进行训练,实现对试件三维微观组分(碳棒、碳纤维束和基体)和缺陷(孔洞、分层和裂纹)的智能识别和分割。结果表明:(1)微观XCT扫描能够高精度表征三维编织C/C复合材料内部组分和缺陷的分布和形态,主要缺陷为相邻纤维束层之间的分层;(2)由于C/C复合材料各微观组分均为碳材料,在CT图像中灰度值相同(或十分接近),难以采用传统阈值算法进行分割;深度学习算法能够有效过滤噪声与伪影并自动精准分割各组分和缺陷,且预测速度比人工图像标注高约两个数量级。本文对三维编织C/C复合材料后续微细观建模和性能优化奠定了基础。

关键词： C/C复合材料微观X射线计算机断层扫描微观组分缺陷深度学习语义分割

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Application of scaled boundary finite element method in static and dynamic fracture problems

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Acta Mechanica Sinica 2006年第3期22卷 243-256页

作者： zhenjun yang College of Civil Engineering and Architecture Zhejiang University Hangzhou 310027 China School of Civil and Resource Engineering The University of Western Australia Crawley WA6009 Australia

The scaled boundary finite element method （SBFEM） is a recently developed numerical method combining advantages of both finite element methods （FEM） and boundary element methods （BEM） and with its own special features as well. One of the most prominent advantages is its capability of calculating stress intensity factors （SIFs） directly from the stress solutions whose singularities at crack tips are analytically represented. This advantage is taken in this study to model static and dynamic fracture problems. For static problems, a remeshing algorithm as simple as used in the BEM is developed while retaining the generality and flexibility of the FEM. Fully-automatic modelling of the mixed-mode crack propagation is then realised by combining the remeshing algorithm with a propagation criterion. For dynamic fracture problems, a newly developed series-increasing solution to the SBFEM governing equations in the frequency domain is applied to calculate dynamic SIFs. Three plane problems are modelled. The numerical results show that the SBFEM can accurately predict static and dynamic SIFs, cracking paths and load-displacement curves, using only a fraction of degrees of freedom generally needed by the traditional finite element methods.

关键词： Scaled boundary finite element method Dynamic stress intensity factors Mixed-mode crack propagation Remeshing algorithm Linear elastic fracture mechanics

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Supramolecular Assembly Models of siRNA Delivery Systems

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中国化学:英文版 2015年第1期33卷 79-89页

作者： Jing Sun Jiancheng Wang zhenjun yang State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical SciencesPeking UniversityBeijing 100191China

Small interfering RNA(siRNA)technology,which could be able to silence specific targeted mRNAs rapidly and efficiently,has been regarded as a novel and potent gene therapeutic approach for diseases,such as cancers,in-fections,inflammations and neurological ***,some conspicuous intrinsic defects of siRNA including the poor cellular uptake,low biological stability,unfavorable pharmacokinetics and bio-distribution properties,have hindered further applications in ***,it is prerequisite to design safe and effective siRNA delivery systems for the successful development of siRNA-based various diseases *** review aims to analyze and summarize these supramolecular assembly models in the process of siRNA delivery,namely recent nanotech-nological strategies for carrying siRNA by using diverse non-viral vehicles such as cationic liposomes,stable nucleic acid lipid particles(SNALPs),cationic polymers,cationic dendrimers,inorganic nanoparticles and ***,it is concluded with future perspectives of siRNA therapeutics in the field of non-viral carriers.

关键词： siRNA delivery supramolecular assembly non-viral vectors nanocarriers

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FINITE ELEMENT MODELLING OF COMPLEX 3D STATIC AND DYNAMIC CRACK PROPAGATION BY EMBEDDING COHESIVE ELEMENTS IN ABAQUS

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Acta Mechanica Solida Sinica 2010年第3期23卷 271-282页

作者： Xiangting Su zhenjun yang Guohua Liu College of Civil Engineering and Architecture Zhejiang University Hangzhou 310027 China Department of Engineering the University of Liverpool L69 3GQ UK

This study proposes an algorithm of embedding cohesive elements in Abaqus and develops the computer code to model 3D complex cragk propagation in quasi-brittle materials in a relatively easy and efficient manner. The cohesive elements with softening traction-separation relations and damage initiation and evolution laws are embedded between solid elements in regions of interest in the initial mesh to model potential cracks. The initial mesh can consist of tetrahedrons, wedges, bricks or a mixture of these elements. Neither remeshing nor objective crack propagation criteria are needed. Four examples of concrete specimens, including a wedgesplitting test, a notched beam under torsion, a pull-out test of an anchored cylinder and a notched beam under impact, were modelled and analysed. The simulated crack propagation processes and load-displacement curves agreed well with test results or other numerical simulations for all the examples using initial meshes with reasonable densities. Making use of Abaqus＇s rich pre/post- processing functionalities and powerful standard/explicit solvers, the developed method offers a practical tool for engineering analysts to model complex 3D fracture problems.

关键词： finite element method cohesive elements three-dimensional crack propagation discrete crack model concrete structures Abaqus

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Synthesis and Antitumor Activity Evaluation of γ-Monofluorinated and γγy-Difluorinated Goniothalamin Analogues

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Chinese Journal of Chemistry 2013年第6期31卷 805-812页

作者： Yi yang zhenjun yang Chunru Cheng Fengling Qing School of Chemistry and Pharmaceutical Engineering Sichuan University of Science & Engineering Zigong Sichuan 643000 China Key Laboratory of Organofluorine Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032 China State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences Peking University 38 Xueyuan Road Beijing 100083 China

A series of novel γ,γ-difluorinated Goniothalamin analogues 4a--4i and 6a--6i were synthesized. The key steps included the construction of C-5 stereocenter adjacent to gem-difluoromethylene group by way of lipase AK catalyzed kinetic resolution, the introduction of aryl group via Stille coupling, and lactonization by 1,5-oxidative cycli- zation. These γ,γ-difluorinated Goniothalamin analogues 4a-4i and their enanfiomers 6a--6i, together with several corresponding 7-monofluorinated Goniothalamin analogues were biologically evaluated against four different cancer cell lines. Compound 7h showed a nearly equivalent potency as the parent （R）-Goniothalamin in the micromolar range. The different fluorine effects between fluoromethylene and gem-difluoromethylene on antitumor activity were discussed through the analysis of bioassay data.

关键词： Goniothalamin Stille coupling fluorine antitumor activity

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Altered acetylcholinesterase levels in the spinal cord anterior horn and dorsal root ganglion following sciatic nerve ischemia

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Neural Regeneration Research 2009年第1期4卷 77-80页

作者： zhenjun yang Pei Wang Songhe yang Jingfeng Xue Department of Human Anatomy Chengde Medical College Chengde 067000 Hebei Province China Affiliated Hospital of Chengde Medical College Chengde 067000 Hebei Province China

BACKGROUND： Peripheral nerve ischemia has been shown to result in ischemic fiber degenera-tion and axoplasmic transport disturbance. However, the effect on acetylcholinesterase （AChE） ex- pression in relevant cells following sciatic nerve ischemia remains unclear. OBJECTIVE： To observe AChE concentration changes following peripheral nerve ischemia. DESIGN, TIME AND SETTING： The present comparative observation, neuroanatomical experiment was performed at the Central Laboratory Animal of Chengde Medical College between 2006 and 2007. MATERIALS： A total of 20 healthy, adult, Wistar rats were randomized into two groups （n = 10）： 8-day ischemia and 14-day ischemia. METHODS： Ischemia injury was induced in the unilateral sciatic nerve （experimental side） through ligation of the common iliac artery. The contralateral side received no intervention, and served as the control side. Rats in the 8-day ischemia and 14-day ischemia groups were allowed to survive for 8 and 14 days, respectively. MAIN OUTCOME MEASURES： The L5 lumbar spinal cord and the L5 dorsal root ganglion were removed from both sides and sectioned utilizing a Leica vibrating slicer. AChE cellular expression was detected using Karnovsky-Root, and the number of AChE-positive cells and average gray value were analyzed using a MiVnt image analysis system. RESULTS： In the 8-day ischemia group, AChE-positive cell numbers were significantly less in the dorsal root ganglion and spinal cord anterior horn of the experimental side, but the average gray value was significantly greater, compared with the control side （P 〈 0.05）. These changes were more significant in the 14-day ischemia group than in the 8-day ischemia group （P 〈 0.01）. CONCLUSION： Peripheral nerve ischemia leads to decreased AChE expression in the associated cells in a time-dependent manner.

关键词： sciatic nerve ischemia acetylcholine esterase neuron

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Sericin protects against diabetes-induced injuries in sciatic nerve and related nerve cells

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Neural Regeneration Research 2013年第6期8卷 506-513页

作者： Chengjun Song zhenjun yang Meirong Zhong Zhihong Chen Department of Human Anatomy Chengde Medical University

Sericin from discarded silkworm cocoons of silk reeling has been used in different fields, such as cosmetology, skin care, nutrition, and oncology. The present study established a rat model of type 2 diabetes by consecutive intraperitoneal injections of low-dose （25 mg/kg） streptozotocin. After intragastrical perfusion of sericin for 35 days, blood glucose levels significantly declined, and the expression of neurofilament protein in the sciatic nerve and nerve growth factor in L4-6 spinal ganglion and anterior horn cells significantly increased. However, the expression of neuropeptide Y in spinal ganglion and anterior horn cells significantly decreased in model rats. These findings indicate that sericin protected the sciatic nerve and related nerve cells against injury in a rat type 2 diabetic model by upregulating the expression of neurofilament protein in the sciatic nerve and nerve growth factor in spinal ganglion and anterior horn cells, and downregulating the expression of neuropeptide Y in spinal ganglion and anterior horn cells.

关键词： neural regeneration traditional Chinese medicine peripheral nerve injury diabetes mellitus sericin sciatic nerve spinal ganglion ceils anterior horn ceils nerve cells neurofilament proteinnerve growth factor neuropeptide Y streptozotocin photographs-containing paper neuroregeneration

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Discussion on the interrelationship among Cu-Ni sulfide deposits,mafic volcanic rocks and intrusive rocks in the Sipu region,northern Guangxi,China

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Chinese Journal Of Geochemistry 2012年第3期31卷 282-296页

作者： yang zhenjun ZHANG Wenshan LIU Jishun YIN Lijun Beijing Institute of Geology and Mineral Resources Beijing 100012China China Nonferrous Metals Mineral Resources Geological Survey Center Donia Resources Co.Ltd.Beijing 100012China School of Geoscience and Environmental Engineering Central South UniversityChangsha 410083China

The Sipu region of North Guangxi is located in the southwest of the "Jiangnan Ancient Land",where there are developed the oldest stratum in southern China,the Proterozoic Sipu Group,and there are also largely ex-posed mafic intrusive rocks,mafic volcanic rocks and copper-nickel sulfide *** mafic intrusive rocks and volcanic rocks are rich in MgO(6.52%-26.39%),but poor in K2O(0.05%-1.00%) and TiO2(0.33%-0.89%).They are also rich in trace elements such as Rb and Ba while poor in Ta,Nb and the *** of them have medium con-tents of rare-earth elements,30.26×10-6-126.71×10-6,in which LREEs are slightly rich with ΣLREE/ΣHREE of 1.35-2.46,δEu 0.79-1.33,displaying weak or no δEu anomaly,with the same geochemical *** right-inclined distribution patterns and the features show that magma would be formed at the comagmatic un-diagenetic *** studies show that mafic intrusive rocks and volcanic rocks are the products of the same source region evolving in different stages and *** copper-nickel sulfide deposits are characterized by liquation,crys-tallization and fractionation of mafic rocks,and have some interrelations with mafic intrusive rocks and volcanic rocks with respect to magmatic genesis.

关键词：铜镍硫化物矿床基性火山岩基性侵入岩中国南方西北部地球化学特征同源岩浆江南古陆

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Estrogen intervention in microvascular morphology and choline acetyltransferase expression in rat hippocampal neurons in chronic cerebral ischemia

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Neural Regeneration Research 2011年第17期6卷 1285-1290页

作者： zhenjun yang Hongwei Yan Guomin Zhang Zhihong Chen Jingfeng xue Department of Anatomy Chengde Medical College Chengde 067000 Hebei Province China Affiliated Hospital.of Chengde Medical College Chengde 067000 Hebei Province China

We observed dynamic changes in microvessels and a protective effect of estrogen on chronic cerebral ischemia ovariectomized rat models established through permanent occlusion of bilateral carotid arteries at 7, 14 and 21 days. The results revealed that estrogen improved microvasculature in the hippocampus of chronic cerebral ischemic rats, upregulated Bcl-2 protein expression, downregulated Bax protein expression, increased choline acetyltransferase expression in hippocampal cholinergic neurons, and suppressed hippocampal neuronal apoptosis. These findings indicate that estrogen can protect hippocampal neurons in rats with chronic cerebral ischemia.

关键词： estrogen chronic cerebral ischemia hippocampus microvasculature Bcl-2 Bax choline acetyltransferase neural regeneration

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