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A Simple 3D Immersed InterfaceMethod for Stokes Flow with Singular Forces on Staggered Grids

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Communications in Computational Physics 2021年第6期30卷 227-254页

作者： Weiyi Wang zhijun tan School of Computer Science and Engineering Sun Yat-sen UniversityGuangzhou 510275China Guangdong Province Key Laboratory of Computational Science Sun Yat-sen Uni-versityGuangzhou 510275China

In this paper,a fairly simple 3D immersed interface method based on the CG-Uzawa type method and the level set representation of the interface is employed for solving three-dimensional Stokes flow with singular forces along the *** method is to apply the Taylor’s expansions only along the normal direction and incorporate the jump conditions up to the second normal derivatives into the finite difference schemes.A second order geometric iteration algorithm is employed for computing orthogonal projections on the surface with third-order *** Stokes equations are discretized involving the correction terms on staggered grids and then solved by the conjugate gradient Uzawa type *** major advantages of the present method are the special simplicity,the ability in handling the Dirichlet boundary conditions,and no need of the pressure boundary *** method can also preserve the volume conservation and the discrete divergence free condition very *** numerical results show that the proposed method is second order accurate and efficient.

关键词： 3D immersed interface method CG-Uzawa method Stokes flow level set method staggered grids singular forces

Condition-based maintenance policy for gamma deteriorating systems

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Journal of Systems Engineering and Electronics 2010年第1期21卷 57-61页

作者： Lin tan zhijun Cheng Bo Guo Shiyu Gong School of Information System and Management National University of Defense Technology Changsha 410073 E R. China

A condition-based maintenance model for gamma deteriorating system under continuous inspection is studied. This methodology uses a gamma distribution to model the material degradation, and the impact of imperfect maintenance actions on the system reliability is investigated. The state of a degrading system immediately after the imperfect maintenance action is assumed as a random variable and the maintenance time follows a geometric process. Furthermore, the explicit expressions for the long-run average cost and availability per unit time of the system are evaluated, an optimal policy （ε^＊） could be determined numeri- cally or analytically according to the optimization model. At last, a numerical example for a degrading system modeled by a gamma process is presented to demonstrate the use of this policy in practical applications.

关键词： condition-based maintenance gamma process imperfect maintenance deteriorating system geometrical process.

Hydrodynamic Interaction of Elastic Capsules in Bounded Shear Flow

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Communications in Computational Physics 2014年第9期16卷 1031-1055页

作者： D.V.Le zhijun tan Institute of High Performance Computing Agency for ScienceTechnology and Research1 Fusionopolis Way#16-16 ConnexisSingapore 138632 School of Mathematics and Computational Science Sun Yat-sen UniversityGuangzhou 510275China Province Key Laboratory of Computational Science Sun Yat-sen UniversityGuangzhou 510275China.

This paper presents a modified Loop’s subdivision algorithm for studying the deformation of a single capsule,the hydrodynamic interaction between two capsules and the hydrodynamic diffusion of a suspension of capsules in bounded shear flow.A subdivision thin-shell model is employed to compute the forces generated on the surface of the elastic capsule during *** capsule surface is approximated using the modified Loop’s subdivision scheme which guarantees bounded curvature and C1 continuity everywhere on the limit *** present numerical technique has been validated by studying the deformation of a spherical capsule in shear *** are also performed for a biconcave capsule over a wide range of shear rates and viscosity ratios to investigate its *** addition,the hydrodynamic interaction between two elastic capsules in bounded shear flow is *** on the wall separation distance,the trajectory-bifurcation points that separate reversing and crossing motions for both spherical and biconcave capsules can be *** to the spherical capsules,the biconcave capsules exhibit additional types of interaction such as rotation and head-on *** head-on collision results in a large trajectory shift which contribute to the hydrodynamic diffusion of a suspension.A suspension of a large number of biconcave capsules in shear flow is also simulated to show the ability of the modified scheme in running a large-scale simulation over a long period of time.

关键词： Thin shell elastic capsules red-blood cells subdivision surfaces immersed boundary method Navier-Stokes equations.

2-羟丙基-β-环糊精降低BDE-47在紫贻贝中的蓄积并减缓其毒性作用

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环境化学 2025年第2期44卷 666-676页

作者：邹亮刘红郭萌萌李风铃谭志军耿倩倩上海海洋大学水产与生命学院上海201306 农业农村部水产品质量安全检测与评价重点实验室中国水产科学研究院黄海水产研究所青岛266071 海水养殖生物育种与可持续产出全国重点实验室中国水产科学研究院黄海水产研究所青岛266071 广东省农产品质量安全风险评估重点实验室广州510640

四溴联苯醚（BDE-47）因其高蓄积性和多毒性特点，引发严重的生态和健康风险，是国际上重点关注和管控的新污染物. 研究通过比较BDE-47单独暴露和BDE-47+2-羟丙基-β-环糊精（HPCD）联合暴露处理的紫贻贝消化盲囊、性腺和鳃等组织中BDE... 详细信息

四溴联苯醚（BDE-47）因其高蓄积性和多毒性特点，引发严重的生态和健康风险，是国际上重点关注和管控的新污染物. 研究通过比较BDE-47单独暴露和BDE-47+2-羟丙基-β-环糊精（HPCD）联合暴露处理的紫贻贝消化盲囊、性腺和鳃等组织中BDE-47蓄积和消除动态差异，测定氧化应激指标和组织损伤，结合分子对接模拟，探讨HPCD对BDE-47蓄积、分布和毒性效应的影响. 结果表明，BDE-47在紫贻贝中的蓄积具有组织特异性;HPCD可显著降低BDE-47在紫贻贝各组织中的蓄积浓度，同时加快BDE-47的消除. HPCD降低了BDE-47在贻贝中的残留风险. GST、SOD、CAT活性和GSH、MDA含量变化分析表明，HPCD减轻了BDE-47对紫贻贝消化盲囊和性腺的氧化胁迫. BDE-47+HPCD处理组的综合生物标志物响应值（IBR）低于BDE-47处理组，组织病理损伤也较轻. 分子对接显示HPCD减轻BDE-47对紫贻贝的毒性，可能是基于HPCD对BDE-47的屏蔽作用. 研究结果为HPCD在减少海洋生物污染物积累和消除方面的应用提供数据支持.

关键词：四溴联苯醚(BDE-47) 羟丙基-β-环糊精(HPCD) 紫贻贝蓄积毒性.

First observation of domoic acid and its isomers in shellfish samples from Shandong Province,China

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Journal of Oceanology and Limnology 2022年第6期40卷 2231-2241页

作者： Guanchao ZHENG Haiyan WU Mengmeng GUO Jixing PENG Yuxiu ZHAI zhijun tan Key Laboratory of Testing and Evaluation for Aquatic Product Safety and Quality Ministry of Agriculture and Rural Aff airsYellow Sea Fisheries Research InstituteChinese Academy of Fishery SciencesQingdao 266071China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266237China Collaborative Innovation Center of Seafood Deep Processing Dalian Polytechnic UniversityDalian 116034China

A total of 133 shellfish samples were collected in seven cities of Shandong Province,China,from May to October,*** domoic acid(DA)concentrations were determined by liquid chromatographytandem mass spectrometry(LC-MS/MS),and their distribution characteristics were *** concentration was detected high in over 1/3(36.1%)of the samples of four kinds of shellfish in all three seasons in range from 0 to 102μg/*** highest DA concentrations were 102,101,36.7,and 10.2μg/kg in Crassostrea gigas,Chlamys farreri,Mactra veneriformis,and Mytilus edulis,***,Yantai(22.0μg/kg)and Weihai(16.9μg/kg)showed relatively high concentrations of DA,whereas Rizhao and Dongying presented only 0.85-and 1.76-μg/kg DA,*** concentrations in the shellfish samples were strongly related to seasonal changes,being significantly higher in autumn and summer than that in *** DA risk exposure assessments indicate that dietary seafood consumption did not pose a health threat to general human *** addition,three isomers(isoA,isoD,isoE)and 5′-epimer DA were detected in 3.00%-15.80%of the shellfish *** study is the first to observe DA and its isomers in shellfish samples of Shandong *** results demonstrate that DA contamination is very common and should be continuously monitored.

关键词： domoic acid shellfi sh liquid chromatography-tandem mass spectrometry(LC-MS/MS) Shandong Province

Thermal processing induced release and degradation of paralytic shellfish toxin from mussels Mytilus edulis

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Journal of Oceanology and Limnology 2022年第6期40卷 2267-2276页

作者： Chenfan DONG Haiyan WU Jixing PENG Mengmeng GUO Yuxiu ZHAI zhijun tan College of Food Science and Technology Shanghai Ocean UniversityShanghai 201306China Key Laboratory of Testing and Evaluation for Aquatic Product Safety and Quality Ministry of AgricultureYellow Sea Fisheries Research InstituteChinese Academy of Fishery SciencesQingdao 266071China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266237China Collaborative Innovation Center of Seafood Deep Processing Dalian Polytechnic UniversityDalian 116034China

Understanding the risk factors associated with shellfish consumption is a relevant public health concern because of the potential adverse ef fects of paralytic shellfish toxins(PSTs).This work aims to study the effects of the five most common heating treatments(steaming,boiling,frying,water-bath heating,and microwaving),for different processing times and temperature/power settings,on the content of PSTs in mussels(Mytilus edulis)collected in Qinhuangdao,*** toxin concentration,removal percentages,and toxin distribution in the cooking liquor and meat were *** five processing modes effectively accelerated toxin release into the cooking *** average percentage removal was 73.53%±16.50%from *** led to the most significant toxin degradation among the methods *** findings should facilitate risk assessment of PSTs in mussels.

关键词： processing mode mussels removal percentage toxin distribution

AnAdaptive Moving Mesh Method for Two-Dimensional Incompressible Viscous Flows

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Communications in Computational Physics 2008年第3期3卷 679-703页

作者： zhijun tan K.M.Lim B.C.Khoo Singapore-MIT Alliance 4 Engineering Drive 3National University of SingaporeSingapore 117576Singapore Department of Mechanical Engineering National University of Singapore10 Kent Ridge CrescentSingapore 119260Singapore.

In this paper, we present an adaptive moving mesh technique for solvingthe incompressible viscous flows using the vorticity stream-function formulation. Themoving mesh strategy is based on the approach proposed by Li et al. [J. Comput. Phys.,170 (2001), pp. 562–588] to separate the mesh-moving and evolving PDE at each timestep. The Navier-Stokes equations are solved in the vorticity stream-function form bya finite-volume method in space, and the mesh-moving part is realized by solving theEuler-Lagrange equations to minimize a certain variation in conjunction with a moresophisticated monitor function. A conservative interpolation is used to redistributethe numerical solutions on the new meshes. This paper discusses the implementationof the periodic boundary conditions, where the physical domain is allowed to deformwith time while the computational domain remains fixed and regular throughout. Numericalresults demonstrate the accuracy and effectiveness of the proposed algorithm.

关键词： Moving mesh method finite volume method Navier-Stokes equations vorticity stream-function incompressible flow.

An Implementation ofMAC Grid-Based IIM-Stokes Solver for Incompressible Two-Phase Flows

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Communications in Computational Physics 2011年第10期10卷 1333-1362页

作者： zhijun tan K.M.Lim B.C.Khoo Guangdong Province Key Laboratory of Computational Science and School of Mathematics and Computational Science Sun Yat-sen UniversityGuangzhou 510275China Singapore-MIT Alliance 4 Engineering Drive 3National University of SingaporeSingapore 117576Singapore Department ofMechanical Engineering National University of Singapore10 Kent Ridge CrescentSingapore 119260Singapore

*** this paper,a novel implementation of immersed interface method combined with Stokes solver on a MAC staggered grid for solving the steady two-fluid Stokes equations with *** velocity components along the interface are introduced as two augmented variables and the resulting augmented equation is then solved by the GMRES *** augmented variables and/or the forces are related to the jumps in pressure and the jumps in the derivatives of both pressure and velocity,and are interpolated using cubic splines and are then applied to the fluid through the jump *** Stokes equations are discretized on a staggered Cartesian grid via a second order finite difference method and solved by the conjugate gradient *** numerical results show that the overall scheme is second order *** major advantages of the present IIM-Stokes solver are the efficiency and flexibility in terms of types of fluid flow and different boundary *** proposed method avoids solution of the pressure Poisson equation,and comparisons are made to show the advantages of time savings by the present *** generalized two-phase Stokes solver with correction terms has also been applied to incompressible two-phase Navier-Stokes flow.

关键词： Incompressible two-phase Stokes equations two-phaseNavier-Stokes equations discontinuous viscosity singular force immersed interface method Uzawa method front tracking method.

Toxic Dinoflagellate Alexandrium tamarense Induces Oxidative Stress and Apoptosis in Hepatopancreas of Shrimp(Fenneropenaeus chinensis)

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Journal of Ocean University of China 2014年第6期13卷 1005-1011页

作者： LIANG Zhongxiu LI Jian LI Jitao tan zhijun REN Hai ZHAO Fazhen College of Fisheries and Life Science Shanghai Ocean University Key Laboratory of Sustainable Development of Marine Fisheries of Ministry of Agriculture Yellow Sea Fisheries Research Institute Chinese Academy of Fishery Sciences

This study investigated the inductive effect ofAlexandrium tamarense, a toxic dinoflagellate producing paralytic shell- fish poison, on oxidative stress and apoptosis in hepatopancreas of Chinese shrimp, Fenneropenaeus chinensis. The individuals of E chinensis were exposed to 200 and 1000 cells mL-1 of A. tamarense with their superoxide dismutase （SOD）, glutathione S-transferase （GST） activities, malonyldialdehyde （MDA） concentration, and caspase gene （FcCasp） expression in hepatopancreas determined at 12, 24, 48, 72 and 96 h. In addition, apoptosis in hepatopancreas of E chinensis at 96 h after exposure was determined through terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling （TUNEL） assay. The hepatopancreatic SOD and GST activities of F. chinensis exposed to 1000 cells mL-1 ofA. tamarense showed a bell-shaped response to exposure time. The hepatopancreatic MDA concentration ofF. chinensis exposed to 1000 cellsmL-1 ofA. tamarense increased gradually from 48 to 96h, and such a trend corresponded to the decrease of GST activity. The hepatopancreatic FcCasp transcript abundance of F. chinensis exposed to 1000 cells mL-1 ofA. tamarense was positively and linearly correlated to MDA concentration. Results of TUNEL assay showed that exposure to 1000 cells mL-1 of A. tamarense induced apoptosis in the hepatopancreas of E chinensis. Our study revealed that A. tamarense exposure influenced the antioxidative status ofF. chinensis and caused lipid peroxidation and apoptosis in the hepatopancreas of shrimp.

关键词： Alexandrium tamarense oxidative stress apoptosis Fenneropenaeus chinensis