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A novel design scheme for acoustic cloaking of complex shape based on region partitioning and multi-origin coordinate transformation

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applied Mathematics and mechanics(English Edition) 2022年第11期43卷 1641-1656页

作者： pengfei LI Fan YANG peng wang Jinfeng ZHAO Zheng ZHONG school of aerospace engineering and applied mechanics Tongji UniversityShanghai 200092China school of Science Harbin Institute of TechnologyShenzhen 518055Guangdong ProvinceChina

Acoustic cloaking is an important application of acoustic *** article proposes a novel design scheme for acoustic cloaking based on the region partitioning and multi-origin coordinate *** cloaked region is partitioned into multiple narrow *** each strip,a local coordinate system is established with the local origin located at the strip center,and a coordinate transformation in the local coordinate system is conducted to squeeze the material along the strip length direction to form the cloaked *** facilitate the implementation of the acoustic cloak,the multilayer effective medium is used to approximate the non-uniform anisotropic material *** effectiveness of the proposed coordinate transformation method is verified by comparing the results from our method with those in the ***,the results of a circular acoustic cloak in the literature are reproduced by using our finite element(FE)simulations for ***,a comparison is made between the traditional coordinate transformation scheme and our new scheme for simulating an elliptical acoustic *** results indicate that the proposed multi-origin coordinate transformation method has a better cloaking effect on the incident wave along the ellipse minor axis direction than the traditional *** means that for the same object,an appropriate transformation scheme can be selected for different incident wave directions to achieve the optimal control *** validated scheme is further used to design an arch-shaped cloak composed of an upper semicircular area and a lower rectangular area,by combining the traditional single-centered coordinate transformation method for the semicircular area and the proposed multi-origin method for the rectangular *** results show that the designed cloak can effectively control the wave propagation with significantly reduced acoustic pressure *** work provides a flexible acoustic cloak design method

关键词： metamaterial acoustic cloak transformation acoustic region partitioning finite element(FE)simulation

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partial wetting of the soft elastic graded substrate due to elastocapillary deformation

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applied Mathematics and mechanics(English Edition) 2023年第8期44卷 1409-1422页

作者： Xu wang Hailiang MA Yonglin YANG Xing LI Yueting ZHOU school of Mathematics and Statistics Ningxia UniversityYinchuan 750021China school of aerospace engineering and applied mechanics Tongji UniversityShanghai 200092China

Surface tension plays a central role in the mechanical behavior of soft materials such as *** deformation of elastic graded substrates is ubiquitous in soft *** this work,the effect of a partially wetting sessile liquid droplet on the elastocapillary deformation of a soft elastic graded substrate is *** modulus is assumed to have an exponential form along the thickness *** applying the Fourier transformation,a mixed boundary-value problem is reduced into a dual integral *** numerical results show that the surface displacement is strongly affected by the inhomogeneity of the *** study of the wetting properties of gel substrates is essential for both understanding the wetting phenomena of gels and developing gels for applications as soft actuators and sensors that can be used in wearable electronics and soft robotics.

关键词： elastocapillary deformation partial wetting gradient integral equation

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recent improvements of actuator line-large-eddy simulation method for wind turbine wakes

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applied Mathematics and mechanics(English Edition) 2021年第4期42卷 511-526页

作者： Zhiteng GAO Ye LI Tongguang wang Shitang KE Deshun LI Jiangsu Key Laboratory of Hi-Tech research for Wind Turbine Design College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210001China school of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 201100China school of Energy and power engineering Lanzhou University of TechnologyLanzhou 730000China College of Civil Aviation Nanjing University of Aeronautics and AstronauticsNanjing 211100China

In a large wind farm,the wakes of upstream and downstream wind turbines can interfere with each other,affecting the overall power output of the wind *** further improve the numerical accuracy of the turbine wake dynamics under atmosphere turbulence,this work proposes some improvements to the actuator line-large-eddy simulation(AL-LES)*** on the dynamic k-equation large-eddy simulation(LES),this method uses a precursor method to generate atmospheric inflow turbulence,models the tower and nacelle wakes,and improves the body force projection method based on an anisotropic Gaussian distribution *** these three improvements,three wind tunnel experiments are used to validate the numerical accuracy of this *** results show that the numerical results calculated in the far-wake region can reflect the characteristics of typical onshore and offshore wind conditions compared with the experimental *** modeling the tower and nacelle wakes,the wake velocity distribution is consistent with the experimental *** radial migration velocity of the tip vortex calculated by the improved blade body force distribution model is 0.32 m/s,which is about 6%different from the experimental value and improves the prediction accuracy of the tip vortex radial *** method proposed in this paper is very helpful for wind turbine wake dynamic analysis and wind farm power prediction.

关键词： actuator line(AL)method large-eddy simulation(LES) wake tip vortex wind turbine

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深部节理岩体开挖卸荷动力破坏机制的离散元研究

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岩土工程学报 2020年第S2期42卷 196-201页

作者：薄英鋆王华宁蒋明镜同济大学地下建筑与工程系上海200092 同济大学航空航天与力学学院上海200092 天津大学建筑工程学院土木工程系天津300350 天津大学水利工程仿真与安全国家重点实验室天津300350

对于高地应力下的岩体开挖,岩体自身的缺陷以及开挖诱发的动力效应对围岩的破坏有十分重要的影响。对节理的分布进行简化与量化,采用二维离散元方法模拟了断续节理岩体中隧道开挖过程,研究不同连通率下岩体的宏观与微观动力破坏模式,以... 详细信息

对于高地应力下的岩体开挖,岩体自身的缺陷以及开挖诱发的动力效应对围岩的破坏有十分重要的影响。对节理的分布进行简化与量化,采用二维离散元方法模拟了断续节理岩体中隧道开挖过程,研究不同连通率下岩体的宏观与微观动力破坏模式,以及节理面附近点处的动力响应。结果表明考虑动力效应后,岩体破坏范围以及程度显著增大;高连通率下动力计算模式更容易产生翼型裂纹的聚合;节理面的存在放大了岩桥中心的动力效应,并对节理面后的岩体起到缓冲作用,但是节理面之前的岩体将会受到反射应力波的影响。

关键词：离散元隧道动力效应断续节理

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基于CiteSpace知识图谱的材料力学课程研究可视化分析

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力学与实践 2024年第2期46卷 447-456页

作者：张锴付昆昆汤可可王华宁郑百林同济大学航空航天与力学学院上海200092

利用知识图谱技术,借助可视化计量分析平台CiteSpace,对中国知网数据库中有关材料力学课程研究的相关文献进行了分析,通过对研究者合作关系、研究机构合作关系以及研究关键词的关联、聚类和演变分析,揭示我国材料力学教学研究现状,展望... 详细信息

利用知识图谱技术,借助可视化计量分析平台CiteSpace,对中国知网数据库中有关材料力学课程研究的相关文献进行了分析,通过对研究者合作关系、研究机构合作关系以及研究关键词的关联、聚类和演变分析,揭示我国材料力学教学研究现状,展望未来的发展趋势。通过可视化分析,得出结论:材料力学教学研究呈现出部分集中、整体分散的态势,基于互联网技术的虚拟教研室有望打破机构间的合作壁垒;研究热点关键词的演化规律符合时代特征,从早期的教材建设和知识点的讲授,到近期的新工科、课程思政和虚拟仿真;结合人工智能技术的辅助教学方法是未来的发展趋势。

关键词：材料力学知识图谱科学计量学可视化

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体育场阶梯型悬挑屋盖风荷载数值模拟研究

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应用力学学报 2019年第5期36卷 1116-1122,1260页

作者：王辉胡贤柱桑立娟合肥工业大学土木与水利工程学院合肥230009 上海中森建筑与工程设计顾问有限公司上海200062

基于CFD数值模拟方法,采用rNG k-ε湍流模型对某体育场阶梯型悬挑屋盖风压进行了模拟研究。分析了屋盖风压分布特性及风向对风压的影响;并且考虑周边建筑对风场的扰动影响,引入风压系数干扰因子IF量化分析了周边建筑对体育场屋盖风压分... 详细信息

基于CFD数值模拟方法,采用rNG k-ε湍流模型对某体育场阶梯型悬挑屋盖风压进行了模拟研究。分析了屋盖风压分布特性及风向对风压的影响;并且考虑周边建筑对风场的扰动影响,引入风压系数干扰因子IF量化分析了周边建筑对体育场屋盖风压分布的气动干扰效应。结果表明:此类阶梯型大跨屋盖主要受风吸力作用,屋盖檐口、角部区域的风压系数量值较大;0°和180°风向角下平均风压随测点位置变化趋势大致相同,风压在台阶转折处发生突变;屋盖各区域的风载体型系数对风向角的敏感程度存在较大差异;周边建筑对屋盖风压主要起遮挡效应,对屋盖某些局部区域的风压起放大效应。

关键词：阶梯型悬挑屋盖平均风压风载体型系数气动干扰数值模拟

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Deformation mode and energy absorption of polycrystal-inspired square-cell lattice structures

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applied Mathematics and mechanics(English Edition) 2020年第10期41卷 1561-1582页

作者： Yijie BIAN puhao LI Fan YANG peng wang Weiwei LI hualin FAN school of aerospace engineering and applied mechanics Tongji UniversityShanghai 200092China research Center of Lightweight Structures and Intelligent Manufacturing State Key Laboratory of Mechanics and Control of Mechanical StructuresNanjing University of Aeronautics and AstronauticsNanjing 210016China

Lattice structures are widely used in many engineering fields due to their excellent mechanical properties such as high specific strength and high specific energy absorption(SEA)*** this paper,square-cell lattice structures with different lattice orientations are investigated in terms of the deformation modes and the energy absorption(EA)*** element(FE)simulations of in-plane compression are carried out,and the theoretical models from the energy balance principle are developed for calculating the EA of these lattice *** agreement is achieved between the FE simulation results and the theoretical *** indicates that the 30◦oriented lattice has the largest EA ***,inspired by the polycrystal microstructure of metals,novel structures of bi-crystal lattices and quad-crystal lattices are developed through combining multiple singly oriented lattices *** results of FE simulations of compression indicate that the EA performances of symmetric lattice bi-crystals and quad-crystals are better than those of the identical lattice polycrystal *** work confirms the feasibility of designing superior energy absorbers with architected meso-structures from the inspiration of metallurgical concepts and microstructures.

关键词： lattice structure quasi-static loading deformation mode energy absorption(EA)

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Gain and laser performance of heavily Er-doped silica fiber fabricated by MCVD combined with the sol-gel method

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Chinese Optics Letters 2021年第11期19卷 27-31页

作者： Qiubai Yang Yan Jiao Chunlei Yu Chongyun Shao Fengguang Lou Shikai wang Lei Zhang Qiuhong Yang Lili hu school of Materials Science and engineering Shanghai UniversityShanghai 200444China Key Laboratory of High power Laser Materials Shanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China

In this work, a heavily Er-doped fiber with an 8 μm core diameter and a numerical aperture of 0.13 was prepared by the modified chemical vapor deposition(MCVD) technique combined with the sol-gel method. The background loss and absorption coefficient at 1530 nm were measured to be 20 d B/km and 128 d B/m, respectively. Thanks to the sol-gel method, the fiber showed a good doping homogeneity, which was confirmed through unsaturable absorption measurement. The net gains of three 25, 45, and 75-cm-long fibers were measured in the range of 1520 to 1600 nm, and the highest gain reached above 23 d B at both 1530 and 1560 nm in 25 and 75-cm-long fibers, respectively. The short-cavity laser performance was measured using centimeter-scale fibers. The maximum output power of 12 m W was demonstrated in a 6.5-cm-long active fiber with a slope efficiency of 20.4%. Overall, the prepared heavily Er-doped silica fiber is a promising item to be applied in a high-repetition-rate or single-frequency fiber laser.

关键词： erbium-doped fiber short-cavity fiber laser sol-gel method

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Simulation of Fusion plasmas:Current Status and Future Direction

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plasma Science and Technology 2007年第3期9卷 312-387页

作者： D.A.Batchelor M.Beck A.Becoulet r.V.Budny C.S.Chang p.H.Diamond J.Q.Dong G.Y.FU A.Fukuyama T.S.Hahm D.E.Keyes Y.Kishimoto S.Klasky L.L.Lao K.Li Z.Lin B.Ludaescher J.Manickam N.Nakajima T.Ozeki N.podhorszki W.M.Tang M.A.Vouk r.E.Waltz S.J.wang H.r.Wilson X.Q.Xu M.Yagi F.Zonca Oak ridge National Laboratory Oak RidgeTN 37831USA 1122 Volunteer Blvd Suite 203KnoxvilleTN 37996-3450USA AssociationEUrATOM-CEA sur la Fusio n Contr■lée CEA Cadarache13108 Saint Paul lez Durance CedexFrance princeton plasma physics Laboratory Princeton UniversityPrincetonNJ 08543USA Courant Institute of Mathematical Sciences New York University251 Mercer StreetNew YorkNY 10012USA university of California at San Diego Dept.of Physics and Center for Astrophysics and Space SciencesLa JollaCA 92093USA Southwestern Institute of physics Chengdu 610041China Department of Nuclear engineering Kyoto UniversityKyoto 606-8501Japan Columbia university Department of Applied Physics and Applied MathematicsMC 4701New YorkNY 10027USA Department of Fundamental Energy Science Graduate School of Energy ScienceKyoto UniversityGokashoUjiKyoto 611-0011Japan General Atomics P.O.Box 85608San DiegoCA 92186USA Department of Computer Science Princeton University PrincetonNJ 08544USA Department of physics and Astronomy University of CaliforniaIrvineCA 92697USA Department of Computer Science university of California DavisCA95616USA National Institute for Fusion Science TokiGifu 509-5292Japan Japan Atomic Energy Agency Naka Fusion Research EstablishmentNaka-machiIbaraki-kenJapan Department of Computer Science North Carolina State UniversityRaleighNC 27695USA Department of physics Fudan University200433 ShanghaiChina Department of physics University of YorkHeslingtonYork YO10 5DD UK Lawrence Livermore National Laboratory LivermoreCA 94550USA research Institute for applied mechanics Kyushu UniversityKasuga 816-8580Japan Associazione Euratom-ENEA sulla fusione CR FrascatiCasella Postale 65-00044FrascatiItaly

I. Introduction (Z. Lin, G. Y. Fu, J. Q. Dong) II. role of theory and simulation in fusion sciences 1. The Impact of theory and simulation on tokomak experiments (H. r. Wilson, T.S. Hahm and F. Zonca) 2. Tokomak Transport physics for the Era of ITEr: Issues for Simulations (p.H. Diamond and T.S. Hahm) III. Status of fusion simulation and modeling 1. Nonlinear Governing Equations for plasma Simulations (T. S. Hahm) 2. Equilibrium and stability (L.L. Lao, J. Manickam) 3. Transport modeling (r.E. Waltz) 4. Nonlinear MHD (G.Y. Fu) 5. Turbulence (Z. Lin and r.E. Waltz) 6. rF heating and current drive (D.A. Batchelor) 7. Edge physics Simulations (X.Q. Xu and C.S. Chang) 8. Energetic particle physics (F. Zonca, G.Y. Fu and S.J. wang) 9. Time-dependent Integrated Modeling (r.V. Budny) 10. Validation and verification (J. Manickam) IV. Major initiatives on fusion simulation 1. US Scientific Discovery through Advanced Computing (SciDAC) program & Fusion Energy Science (W. Tang) 2. EU Integrated Tokamak Modelling (ITM) Task Force (A. Becoulet) 3. Fusion Simulations Activities in Japan (A. Fukuyama, N. Nakajima, Y. Kishimoto, T. Ozeki, and M. Yagi) V. Cross-disciplinary research in fusion simulation 1. applied mathematics: Models, Discretizations, and Solvers (D.E. Keyes) 2. Computational Science (K. Li) 3. Scientific Data and Workflow Management (S. Klasky, M. Beck, B. Ludaescher, N. podhorszki, M.A. Vouk) 4. Collaborative tools (J. Manickam)

关键词： mode ITEr

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水下浅埋双孔平行隧道渗流场的解析研究

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岩土工程学报 2021年第6期43卷 1088-1096,F0003页

作者：郭玉峰王华宁蒋明镜同济大学航空航天与力学学院上海200092 同济大学土木工程防灾国家重点实验室上海200092 天津大学土木工程学院天津300072

目前对于双孔隧道渗流场的解析求解多基于单孔隧道渗流场的简单叠加,未真实满足洞周边界条件,所得结果存在误差。基于质量守恒定律和达西定律,采用保角变换法和Schwartz迭代法对水下双线平行隧道稳态渗流场进行了推导,经过2~3次迭代后... 详细信息

目前对于双孔隧道渗流场的解析求解多基于单孔隧道渗流场的简单叠加,未真实满足洞周边界条件,所得结果存在误差。基于质量守恒定律和达西定律,采用保角变换法和Schwartz迭代法对水下双线平行隧道稳态渗流场进行了推导,经过2~3次迭代后获得了高精度的解答。采用Comsol软件对该问题进行数值模拟,并将数值模拟结果与本文解析解进行对比,发现在全域范围二者均吻合良好。与叠加法解答的对比显示,本解答与叠加法解答在远区一致;而隧道附近叠加法的误差较大。最后,讨论了隧道间距、埋深和相对大小对双孔平行隧道渗流场水头分布、渗流量的影响。

关键词：双孔平行隧道渗流场解析解 Schwartz迭代法保角变换

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