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A Fourier Spectral Moving Mesh Method for the Cahn-Hilliard Equation with Elasticity

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Communications in Computational Physics 2009年第2期5卷 582-599页

作者： W.M.Feng P.Yu S.Y.Hu Z.K.Liu q.du L.q.Chen Department of Materials Science and Engineering Pennsylvania State UniversityUniversity ParkPA 16802USA Department of Mathematics Pennsylvania State UniversityUniversity ParkPA 16802USA Pacific Northwest National Laboratory RichlandWA 99354USA

In recent years,Fourier spectral methods have emerged as competitive numerical methods for large-scale phase field simulations of microstructures in computational materials *** further improve their effectiveness,we recently developed a new adaptive Fourier-spectral semi-implicit method(AFSIM)for solving the phase field equation by combining an adaptive moving mesh method and the semi-implicit Fourier spectral *** this paper,we present the application of AFSIM to the Cahn-Hilliard equation with inhomogeneous,anisotropic *** implementations and test examples in both two and three dimensions are considered with a particular illustration using the well-studied example of mis-fitting particles in a solid as they approach to their equilibrium *** is shown that significant savings in memory and computational time is achieved while accurate solutions are preserved.

关键词： Phase field diffuse interface moving mesh adaptive mesh Fourier-spectral method adaptive spectral method Cahn-Hilliard equation elasticity

Microstructure evolution during homogenization of Al-Mg-Si-Mn-Fe alloys: Modelling and experimental results

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Transactions of Nonferrous Metals Society of China 2017年第4期27卷 747-753页

作者： C.L.LIU H.AZIZI-ALIZAMINI N.C.PARSON W.J.POOLE q.du Department of Materials Engineering The University of British Columbia Vancouver V6T 1Z4 Canada Department of Materials Science and Engineering Mc Master University Hamilton L8S 4L7 Canada Rio Tinto Arvida Research and Development Centre P. O. Box 1250 Jonquière (QC) G7S 4K8 Canada SINTEF Materials and Chemistry P. O. Box 4760 Sluppen 7456 Trondheim Norway

Microstructure evolution during the homogenization heat treatment of an Al?Mg?Si?Fe?Mn(AA6xxx)alloy wasinvestigated using a combination of modelling and experimental *** model is based on the CALPHAD-coupledhomogenization heat treatment model originally developed for AA3xxx alloys(i.e.,Al?Mn?Fe?Si).In this work,the model wasadapted to the more complex AA6xxx system(Al?Mg?Si?Mn?Fe)to predict the evolution of critical microstructural features suchas the spatial distribution of solute,the type and fraction of constituent particles and dispersoid number density and size *** were also conducted using three direct chill(DC)cast AA6xxx alloys with different Mn levels subjected to varioushomogenization *** resulting microstructures were characterized using a range of techniques including scanning electronmicroscopy,electron microprobe analysis(EPMA),XRD,and electrical resistivity *** model predictions werecompared with the experimental measurements,and reasonable agreement was found.

关键词： AA6xxx alloy homogenization heat treatment mathematical modelling CALPHAD diffusion

Spalling characteristics of high-temperature treated granitic rock at different strain rates

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1280-1288页

作者： L.F.Fan q.H.Yang X.L.du The Key Laboratory of Urban Security and Disaster Engineering of Ministry of Education Beijing University of TechnologyBeijing100124China

The dynamic spalling characteristics of rock are important for stability analysis in rock *** paper presented an experimental investigation on the dynamic spalling characteristics of granite with different temperatures and strain rates.A series of dynamic spalling tests with different impact velocities were conducted on thermally treated granite at different *** dynamic spalling strengths of granite with different temperatures and strain rates were determined.A model was proposed to correlate the dynamic spalling strength of granite,high temperature and strain *** results show that the spalling strength of granite decreases with increasing ***,the spalling strength of granite with a higher strain rate is larger than that with a lower strain *** proposed model can describe the relationship among dynamic spalling strength of granite,high temperature and strain rate.

关键词： Dynamic spalling characteristics High temperature Strain rate Dynamic loading Granite

Electron kinetic effects in back-stimulated Raman scattering bursts driven by broadband laser pulses

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Matter and Radiation at Extremes 2024年第4期9卷 54-67页

作者： q.K.Liu L.Deng q.Wang X.Zhang F.q.Meng Y.P.Wang Y.q.Gao H.B.Cai S.P.Zhu Graduate School China Academy of Engineering PhysicsBeijing 100088China Institute of Applied Physics and Computational Mathematics Beijing 100094China School of Nuclear Science and Technology University of Science and Technology of ChinaHefei 230026China Shanghai Institute of Laser Plasma Shanghai 201800China HEDPS Center for Applied Physics and TechnologyPeking UniversityBeijing 100871China School of Physics Zhejiang UniversityHangzhou 310027China

We examine electron kinetic effects in broadband-laser-driven back-stimulated Raman scattering(BSRS)bursts using particle-in-cell *** bursts occur during the nonlinear stage,causing reflectivity spikes and generating large numbers of hot ***-duration simulations are performed to observe burst events,and a simplified model is developed to eliminate the interference of the broadband laser’s random intensity *** the simplified model,we isolate and characterize the spectrum of electron plasma *** spectrum changes from a sideband structure to a turbulence-like structure during the burst.A significant asymmetry in the spectrum is *** asymmetry is amplified and transferred to electron phase space by high-intensity broadband laser pulses,leading to violent vortex-merging and generation of hot *** proportion of hot electrons increases from 6.76%to 14.7%during a single violent burst *** demonstrate that kinetic effects profoundly influence the BSRS evolution driven by broadband lasers.

关键词： scattering kinetic simplified

Solute flow and particle transport in aquatic ecosystems: A review on the effect of emergent and rigid vegetation

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Environmental Science and Ecotechnology 2024年第5期21卷 77-91页

作者： Judy q.Yang St.Anthony Falls Laboratory Department of CivilEnvironmentaland Geo-EngineeringUniversity of Minnesota Twin CitiesMNUSA

In-channel vegetation is ubiquitous in aquatic environments and plays a critical role in the fate and transport of solutes and particles in aquatic *** studies have advanced our understanding of the role of vegetation in solute flow and particle transport in aquatic *** review summarizes these papers and discusses the impacts of emergent and rigid vegetation on the surface flow,the advection and dispersion of solutes,suspended load transport,bedload transport,and hyporheic *** two competing effects of emergent vegetation on the above transport processes are *** the one hand,emergent vegetation reduces mean flow velocity at the same surface slope,which reduces mass *** the other hand,at the same mean flow velocity,vegetation generates turbulence,which enhances mass *** understanding of these two competing effects and predictive equations derived from laboratory experiments are *** equations for the mean flow velocity and turbulent kinetic energy inside an emergent vegetation canopy are derived based on force and energy *** impacts of emergent vegetation on the advection-dispersion process,the suspended load and bedload transport,and the hyporheic exchange are *** impacts of other vegetation-related factors,such as vegetation morphology,submergence,and flexibility,are briefly *** role of vegetation in transporting other particles,such as micro-and macro-plastics,is also briefly ***,suggestions for future research directions are proposed to advance the understanding of the dynamic interplays among natural vegetation,flow dynamics,and sedimentary processes.

关键词： transport load flow

Topology of charged AdS black hole in restricted phase space

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Chinese Physics C 2024年第9期48卷 291-299页

作者： Han Wang Yun-Zhi du College of Mathematics and Statistics Shanxi Datong UniversityDatong 037009China Department of Physics Shanxi Datong UniversityDatong 037009China Institute of Theoretical Physics Shanxi Datong UniversityDatong 037009China

The local topological properties of black hole systems can be expressed through winding numbers as *** date,AdS black hole thermodynamics are often depicted by the dual parameters of(T,S),(P,V),(Φ,q) in the extended phase space,while there have been several studies on the black hole thermodynamics in the restricted phase *** this paper,we analyze the topological properties of charged AdS black holes in the restricted phase space under the higher-dimension and higher-order curvature gravity *** results show that the topological number of the charged black hole in the same canonical ensembles is a constant and is independent of the concrete dual thermodynamical ***,the topological number in the grand canonical ensemble is different from that in the canonical ensemble for the same black hole ***,these results are independent of dimension d and highe st order k of the Lanczos-Lovelock densities.

关键词： topology phase transition black hole

Toeplitz Operators and Carleson Measures for Weighted Bergman Spaces Induced by Regular Weights

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Acta Mathematica Sinica,English Series 2024年第5期40卷 1345-1359页

作者： Jun Tao du Song Xiao Hasi WULAN Department of Mathematics Guangdong University of Petrochemical TechnologyMaoming 525000P.R.China Department of Mathematics Shantou UniversityShantou 515063P.R.China

In this paper,we give a universal description of the boundedness and compactness of Toeplitz operator T_(μ)^(ω)between Bergman spaces A_(η)^(p)and A_(υ)^(q)whenμis a positive Borel measure,1q<∞andω,η,υare ... 详细信息

关键词： Bergman space Carleson measure Toeplitz operator regular weight

Precipitation of multi-type nano-quasicrystals in a Mg-Zn-Y alloy

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Journal of Magnesium and Alloys 2024年第3期12卷 997-1008页

作者： W.Z.Wang X.Z.Zhou L.F.Zhang H.q.Ye Z.q.Yang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of ScienceShenyang 110016China Ji Hua Laboratory Foshan 528251China Foshan University Foshan 528231China

Mg-6Zn-1Y(at.%)ribbons with strengthening precipitates of multi-type nanoquasicrystals were prepared by melt-spinning followed by aging *** evolution of the rapidly solidified ribbons during isothermal aging was comprehensively studied using various electron microscopy *** new kinds of decagonal quasicrystals were formed in aged ribbons,in addition to precipitation of nanometer icosahedral ***-resolution observations reveal that both decagonal quasicrystals can be modeled by quasiperiodic tiling with decagonal clusters of 2.5 nm in diameter,but overlap of neighboring clusters in both decagonal quasicrystals is different from the Gummelt model observed in other quasicrystals.A shell composed of complex Laves Mg-Zn domains was formed surrounding each decagonal quasicrystal precipitate upon prolonged *** addition,all kinds of nanoprecipitates exhibit excellent structure and size stability at 573 *** findings may have implications for not only fundamental studies about quasicrystals,but also microstructural manipulation of high-performance Mg alloys.

关键词： quasicrystal Mg alloys Rapid solidification Scanning-transmission electron microscopy.

A Hybrid Signal Processing Method Combining Mathematical Morphology and Walsh Theory for Power quality Disturbance Detection and Classification

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 584-592页

作者： Zhi Ding Tianyao Ji Mengshi Li q.H.Wu School of Electric Power Engineering South China University of Technology(SCUT)Guangzhou 510641China

In this paper, a novel signal processing method combining mathematical morphology (MM) and Walsh theory is proposed, which uses Walsh functions to control the structuring element (SE) and MM operators. Based on the Walsh-MM method, a scheme for power quality disturbances detection and classification is developed, which involves three steps: denoising, feature extraction and morphological clustering. First, various evolution rules of Walsh function are used to generate groups of SEs for the multiscale Walsh-ordered morphological operation, so the original signal can be denoised. Next, the fundamental wave of the denoised signal is suppressed by Hadamard matrix;thus, disturbances can be extracted. Finally, the Walsh power spectrum of the waveform extracted in the previous step is calculated, and the parameters of which are taken by morphological clustering to classify the disturbances. Simulation results reveal the proposed scheme can effectively detect and classify disturbances, and the Walsh-MM method is less affected by noise and only involves simple calculation, which has a potential to be implemented in hardware and more suitable for real-time application.

关键词： Hadamard matrix mathematical morphology morphological clustering power quality disturbance Walsh theory