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A high Order Bound Preserving Finite Difference Linear Scheme for Incompressible Flows

Communications in Computational Physics 2022年第6期32卷 126-155页

作者： Guoliang Zhang Tao Xiong School of Mathematical Sciences Xiamen UniversityXiamenFujian 361005P.R.China School of Mathematical Sciences and Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific Computing Xiamen UniversityXiamenFujian 361005P.R.China

We propose a high order finite difference linear scheme combined with ahigh order bound preserving maximum-principle-preserving (MPP) flux limiter tosolve the incompressible flow system. For such problem with highly oscillatory structure but not strong shocks, our approach seems to be less dissipative and much lesscostly than a WENO type scheme, and has high resolution due to a Hermite reconstruction. Spurious numerical oscillations can be controlled by the weak MPP fluxlimiter. Numerical tests are performed for the Vlasov-Poisson system, the 2D guidingcenter model and the incompressible Euler system. The comparison between the linearand WENO type schemes, with and without the MPP flux limiter, will demonstrate thegood performance of our proposed approach.

关键词： Finite difference scheme high order Hermite reconstruction MPP flux limiter incompressible flow Vlasov-Poisson

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Kinematics Analysis of Multi-link Mechanisms Under the Interaction of Motion Pair Clearance and Elastic Links 2nd

Kinematics Analysis of Multi-link Mechanisms Under the Inter...

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2nd International Conference of Mechanical System Dynamics, ICMSD 2023

作者： Huang, Juan Zhou, Dang Wang, Hongbing Yin, Lairong College of Mechanical and Electrical Engineering Hunan Agriculture University Changsha410012 China School of Automotive and Mechanical Engineering Changsha University of Science and Technology Changsha410114 China Hunan Provincial Key Laboratory of Intelligent Manufacturing Technology for High-Performance Mechanical Equipment Changsha University of Science and Technology Changsha410114 China

ISBN: (纸本)9789819980475

A dynamic model for a rigid–flexible coupling multi-link mechanism with motion pair clearance is established in this work. The contact-impact force is used to describe the clearance between the joints. Then, the frictional force is expressed by a modified Coulomb model, and the drive link is flexibly modified by ANSYS. Furthermore, ADAMS simulation software is used to solve the influences of clearance, flexibility, and load on the displacement, speed, and acceleration of the multi-link mechanism. The simulation results show that the clearance size, the number of clearances, the flexibility, and the load have different effects on the dynamic response of the multi-link mechanism, and that the impact of load and flexibility is relatively large. This work offers guidance for the dynamic optimization design of multi-link mechanisms, and is significant for analyzing the motion accuracy of multi-link mechanisms. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024.

关键词： Kinematics

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Yb:CaF_(2)-YF_(3)transparent ceramics ultrafast laser at dual gain lines

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Chinese Physics B 2022年第11期31卷 336-340页

作者： Xiao-Qin Liu Qian-Qian Hao Jie Liu Dan-Hua Liu Wei-Wei Li Liang-Bi Su Shandong Provincial Key Laboratory of Optics and Photonic Device School of Physics and ElectronicsShandong Normal UniversityJinan 250358China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 201899China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

Yb^(3+):CaF_(2)–YF_(3)transparent ceramics with excellent optical quality was successfully fabricated by hot-pressed *** laser properties of this ceramics were investigated for the first *** diode(LD)was applied as the pump source to generate a dual-wavelength mode-locked(ML)*** maximum average output power was 310 mW,which represents the highest output power of ultrafast calcium fluoride ceramic *** spectrum separated at 1048.9 nm and 1049.7 nm with a total pulse duration of 8.9 *** interval period between the beating signals was about 4.3 ps,corresponding to a 0.23 THz beat pulse repetition *** results demonstrate its potential in producing dual-wavelength ultrashort *** Yb^(3+):CaF_(2)–YF_(3)ceramics with low-cost and short-preparation period are ideal candidate materials for ultrafast lasers.

关键词： transparent ceramics passively mode-locking dual-wavelength laser

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Efficient SVV stabilized triangular spectral element methods for incompressible flows of high Reynolds numbers

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Advances in Aerodynamics 2022年第1期4卷 58-77页

作者： Lizhen Chen Tao Tang Chuanju Xu Beijing Computational Science Research Center Beijing100193People’s Republic of China Division of Science and Technology BNU-HKBU United International CollegeZhuhaiGuangdongPeople’s Republic of China Guangdong Provincial Key Laboratory of Computational Science and Material Design Southern University of Science and TechnologyShenzhenPeople’s Republic of China School of Mathematical Sciences and Fujian Provincial Key Laboratory of Mathematical Modeling and High-Performance Scientific ComputingXiamen UniversityXiamen361005People’s Republic of China

In this paper,we propose a spectral vanishing viscosity method for the triangular spectral element computation of high Reynolds number incompressible *** can be regarded as an extension of a similar stabilization technique for the standard spectral element *** difficulty of this extension lies in the fact that a suitable definition of spectral vanishing viscosity operator in non-structured elements does not exist,and it is not clear that if a suitably defined spectral vanishing viscosity provides desirable dissipation for the artificially accumulated *** main contribution of the paper includes:1)a well-defined spectral vanishing viscosity operator is proposed for non-standard spectral element methods for the Navier-Stokes equations based on triangular or tetrahedron partitions;2)an evaluation technique is introduced to efficiently implement the stabilization term without extra computational cost;3)the accuracy and efficiency of the proposed method is carefully examined through several numerical *** numerical results show that the proposed method not only preserves the exponential convergence,but also produces improved accuracy when applied to the unsteady Navier-Stokes equations having smooth ***,the stabilized triangular spectral element method efficiently stabilizes the simulation of high Reynolds incompressible flows.

关键词： Navier-Stokes equations Triangular spectral element method Spectral vanishing viscosity

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A Mixed Finite Element Scheme for Biharmonic Equation with Variable Coefficient and von Kármán Equations

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Communications in Computational Physics 2022年第5期31卷 1434-1466页

作者： Huangxin Chen Amiya K.Pani Weifeng Qiu School of Mathematical Sciences and Fujian Provincial Key Laboratory on MathematicalModeling and High Performance Scientific Computing Xiamen UniversityFujian361005China Department of Mathematics Indian Institute of TechnologyBombayPowaiMumbai-400076India Department of Mathematics City University of Hong Kong83 Tat Chee AvenueKowloonHong KongChina

In this paper,a new mixedfinite element scheme using element-wise stabilization is introduced for the biharmonic equation with variable coefficient on Lipschitz polyhedral *** proposed scheme doesn’t involve any integration along mesh *** gradient of the solution is approximated by H(div)-conforming BDMk+1 element or vector valued Lagrange element with order k+1,while the solution is approximated by Lagrange element with order k+2 for any k≥*** scheme can be easily implemented and produces symmetric and positive definite linear *** provide a new discrete H^(2)-norm stability,which is useful not only in analysis of this scheme but also in C^(0) interior penalty methods and DG *** convergences in both discrete H^(2)-norm and L^(2)-norm are *** scheme with its analysis is further generalized to the von K´arm´an ***,numerical results verifying the theoretical estimates of the proposed algorithms are also presented.

关键词： Biharmonic equation von K´arm´an equations mixedfinite element methods element-wise stabilization discrete H2-stability positive definite

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Exfoliation Corrosion of As‑Extruded Mg–1Li–1Ca:the Influence of the Superficial Layer

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1339-1353页

作者： Ze‑Song Wei Zi‑You Ding Lei Cai Shao‑Xia Ma Dong‑Qing Zhao Lan‑Yue Cui Cheng‑Bao Liu Yuan‑Sheng Yang Yuan‑Ding Huang Rong‑Chang Zeng Corrosion Laboratory for Light Metals College of Materials Science and EngineeringShandong University of Science and TechnologyQingdao 266590China Engineering Research Center for Magnesium‑Based New Materials Center for Advancing Materials Performance from the Nanoscale(CAMP‑Nano)State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049China Shandong Provincial Key Laboratory of High Strength Lightweight Metallic Materials Advanced Materials InstituteQilu University of Technology(Shandong Academy of Sciences)Jinan 250014China Institute of Metals Research Chinese Academy of SciencesShenyang 110016China Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax‑Planck‑Str.121502 GeesthachtGermany

Exfoliation corrosion(EFC)has rarely been reported for wrought magnesium *** EFC of the as-extruded Mg–1Li–1Ca alloy was observed after the removal of outermost fine-grained *** microstructure and corrosion products were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,X-ray diffraction,and Fourier transform infrared *** corrosion behavior was analyzed using electrochemical polarization,electrochemical impedance spectroscopy,and scanning Kelvin probe *** results indicated that the surface of Mg–1Li–1Ca,with the superficial layer removed,was more susceptible to EFC.A linear correlation between grain boundary density and corrosion resistance was ***,the influence of factors such as grain size,intermetallic compounds,different alloy surfaces,and corrosion products on EFC were discussed,and the corresponding EFC mechanism was clarified.

关键词： Magnesium alloys Exfoliation corrosion Microstructure Intermetallic compound Metamorphic skin

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Pronounced advance on typhoon track forecast with global convection-permitting model

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Science Bulletin 2025年第9期70卷 1424-1428页

作者： Gu, Jun Zhao, Chun Li, Gudongze Feng, Jiawang Xu, Mingyue Du, Qiuyan Xia, Zihan Li, Yubin Chen, Guanghua Hao, Xiaoyu Chen, Junshi An, Hong Deep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software University of Science and Technology of China Hefei230026 China Laoshan Laboratory Qingdao266237 China CAS Center for Excellence in Comparative Planetology University of Science and Technology of China Hefei230026 China School of Atmospheric Physics Nanjing University of Information Science and Technology Nanjing210044 China Key Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences Beijing100029 China School of Computer Science and Technology University of Science and Technology of China Hefei230026 China

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Effect of extrusion ratio on microstructure and mechanical properties of AZ42 alloy sheet

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Transactions of Nonferrous Metals Society of China 2025年第4期35卷 1109-1121页

作者： Song-ke XIAO Xiao-jie ZHOU Gang ZENG Hong-chao XIAO Xin-kai KANG Xian-zheng LU Xiao-min CHEN Jian ZHANG Hunan Provincial Key Laboratory of Intelligent Manufacturing Technology for High-performance Mechanical Equipment Changsha University of Science and TechnologyChangsha 410114China Hunan Provincial Key Laboratory of Advanced Aerospace Materials CASIC(Changsha)Advanced Materials Institute Co.Ltd.Changsha 410221China Hunan Provincial Engineering Research Center of Wrought Magnesium Alloys and Surface Protection Changsha 410221China SJTU−Yibin Innovation Center for Advanced Materials Yibin 644002China

The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical microscopy,scanning electron microscopy,energy dispersive spectrometry and electron backscatter *** results show that extrusion produces a typical basal fiber texture and streamlines of second *** samples exhibit the lowest Schmid factor of basal slip(SFb)and the superior tensile yield strength(TYS)along extrusion direction(ED).The sample with extrusion ratio of 20 exhibits the largest average grain size,but the smallest SFb which compensates for the disadvantage of grain coarsening and maintains the *** being peak-aged at 175℃for 48 h,the sample with the extrusion ratio of 20 shows the optimal TYS along all the directions,compared to the other *** hopes to provide useful information for optimizing the deformation parameters of the AZ42 alloys.

关键词： AZ42 alloy extrusion ratio Schmid factor strength aging-hardening

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Efficient quantum process tomography for Clifford circuits

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Physical Review A 2023年第3期108卷 032419-032419页

作者： Shichuan Xue Guangyao Huang Yong Liu Dongyang Wang Weixu Shi Yingwen Liu Xiang Fu Anqi Huang Mingtang Deng Junjie Wu Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha 410073 China

A Clifford circuit is a pivotal tool in quantum computing and has extensive applications in quantum error correction codes and topological quantum computing. Hence, it is essential to benchmark and verify the effect of Clifford circuits against noise and errors. Standard quantum process tomography is a fundamental technique for fully characterizing quantum dynamics, but at the cost of exponential time, space, and computation with an increasing number of qubits. Here, we propose an efficient quantum process tomography method for Clifford circuits. Combining with the stabilizer formalism, we prove theoretically that, for an n-qubit Clifford circuit, our method merely needs m ancillary qubits and ⌈n/m⌉ input stabilizer states to obtain the quantum process. Numerical simulation results show that our method could perfectly rebuild the unknown Clifford quantum circuit with fidelity over 99.99% to six qubit cases. Our work provides an efficient and practical approach to benchmark and verify Clifford circuits.

关键词： Quantum circuits Quantum information processing Quantum simulation Quantum tomography

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Person Re-Identification Based on Multi-Spectrum Information Aggregation Transformers

Person Re-Identification Based on Multi-Spectrum Information...

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International Conference on Image, Vision and computing (ICIVC)

作者： Yuxuan Zhang Huibin Tan Long Lan Jing Ren Xiao Teng State Key Laboratory of High Performance Computing National University of Defense Technology Changsha China

Convolutional Neural Networks (CNNs) have achieved remarkable success in various image-related tasks. However, CNNs' chunking approach of sliding windows over pixels hinders its ability to learn sequential semantic information. To address this issue, researchers have proposed models that integrate Transformers to aggregate features across different resolutions, taking advantage of the Transformer's strengths. Hierarchical Aggregation Transformer (HAT) is one such model that integrates low-level and high-level details, showing a great effect on person re-identification. Based on HAT, we propose the Multi-Spectrum Information Aggregation Transformers (MIAT), which enhances the low-level structural information captured by CNNs through a frequency channel attention module that extracts multi-spectral features. By leveraging discrete cosine transform (DCT), more detailed features can be learned to improve person re-identification, enabling better discernment of distinguishing features between different individuals. Through extensive experimentation, we validate our model's performance on two widely employed person re-identification datasets and demonstrate its superiority over existing advanced methods.

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