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Communications in Computational Physics 2009年第2期5卷 760-778页

作者： Yuzhi Sun z.j.wang Yen Liu Department of Aerospace Engineering Iowa State UniversityAmesIA 50011USA NASA Ames Research Center Moffett FieldCA 94035USA

An implicit non-linear lower-upper symmetric Gauss-Seidel(LU-SGS)solution algorithm has been developed for a high-order spectral difference Navier-Stokes solver on unstructured hexahedral *** non-linear LU-SGS solver is preconditioned by a block element matrix,and the system of equations is then solved with the LU decomposition *** large sparse jacobian matrix is computed numerically,resulting in extremely simple operations for arbitrarily complex residual *** inviscid and viscous test cases were performed to evaluate the *** implicit solver has shown speedup of 1 to 2 orders of magnitude over the multi-stage Runge-Kutta time integration scheme.

关键词： High order unstructured grids spectral difference Navier-Stokes implicit

Performance of Low-Dissipation Euler Fluxes and Preconditioned LU-SGS at Low Speeds

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Communications in Computational Physics 2011年第6期10卷 90-119页

作者： Keiichi Kitamura Eiji Shima Keiichiro Fujimoto z.j.wang jAXA’s Engineering Digital Innovation(jEDI)Center Japan Aerospace Exploration Agency3-1-1 YoshinodaiChuuouSagamiharaKanagawa252-5210Japan jAXA’s Engineering Digital Innovation(jEDI)Center Japan Aerospace Exploration Agency2-1-1 SengenTsukubaIbaraki305-8505Japan Department of Aerospace Engineering Iowa State University2271 Howe HallAmesIA 50011USA.

In low speed flow computations,compressible finite-volume solvers are known to a)fail to converge in acceptable time and b)reach unphysical *** problems are known to be cured by A)preconditioning on the time-derivative term,and B)control of numerical dissipation,*** have been several methods of A)and B)proposed ***,it is unclear which combination is the most accurate,robust,and efficient for low speed *** carried out a comparative study of several well-known or recently-developed low-dissipation Euler fluxes coupled with a preconditioned LU-SGS(Lower-Upper Symmetric Gauss-Seidel)implicit time integration scheme to compute steady *** a series of numerical experiments,accurate,efficient,and robust methods are suggested for low speed flow computations.

关键词： All-speed scheme low-dissipation preconditioning LU-SGS

Optimal phase estimation with photon-number difference measurement using twin-Fock states of light

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Chinese Physics B 2019年第12期28卷 82-87页

作者： jH Xu j z wang A X Chen Y Li G R jin Key Laboratory of Optical Field Manipulation of zhejiang Province and Physics Department of zhejiang Sci-Tech University Hangzhou 310018China Beijing Computational Science Research Center.Beijing 100193 China

Quantum phase measurement with multiphoton twin-Fock states has been shown to be optimal for detecting equal numbers of photons at the output ports of a Mach–zehnder interferometer(i.e., the so-called single-fringe detection), since the phase sensitivity can saturate the quantum Cramér–Rao lower bound at certain values of phase shift. Here we report a further step to achieve a global phase estimation at the Heisenberg limit by detecting the particle-number difference(i.e., the ?_z measurement). We show the role of experimental imperfections on the ultimate estimation precision with the six-photon twin-Fock state of light. Our results show that both the precision and the sensing region of the ?_z measurement are better than those of the single-fringe detection, due to combined contributions of the measurement outcomes. We numerically simulate the phase estimation protocol using an asymptotically unbiased maximum likelihood estimator.

关键词： foundations of quantum mechanics measurement theory nonclassical interferometry

In situ digital testing method for quality assessment of soft soil improvement with polyurethane

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journal of Rock Mechanics and Geotechnical Engineering 2024年第5期16卷 1732-1748页

作者： X.F.wang C.j.wang W.V.Yue z.j.zhang z.Q.Yue Department of Civil Engineering China University of Geosciences (Beijing)BeijingChina Department of Water Science and Engineering Zhengzhou UniversityZhengzhouChina Department of Geotechnical Engineering Tongji UniversityShanghaiChina Department of Civil Engineering The University of Hong KongChina

This study purposes an in situ testing method on quality assessment of soil *** drilling data includes the spatial distribution and in situ strength of untreated and treated soil along three different drillholes measured by on-site drilling monitoring *** factual drilling data can characterize the degree of soil improvement by penetration injection with permeable *** from on-site drilling monitoring shows that the linear zones represent constant drilling speeds shown in the plot of drill bit advancement *** drilling time,which indicates the spatial distributions of soil *** soil profile at the study site is composed of four layers,which includes fill,untreated silty clay,treated silty clay,and mucky *** results of soil profile are verified by the parallel site *** constant drilling speeds profile the coring-resistant strength of drilled *** comparing with the untreated silty clay,the constant drilling speeds of the treated silty clay have been decreased by 13.0-62.8%.Two drilling-speed-based indices of 61.2%and 65.6%are proposed to assess the decreased average drilling speed and the increased in situ strength of treated silty *** tests,*** compressive strength(UCS)test,have been performed with core sample to investigate and characterize in situ strength by comparing that with drilling *** show that the average predicted strengths of treated silty clay are 2.4-6.9 times higher than the average measured strength of untreated silty *** UCS-based indices of 374.5%and 344.2%verified the quality assessment(QA)results by this new in situ *** method provides a cost-effective tool for quality assessment of soil improvement by utilizing the digital drilling data.

关键词： Drilling process monitoring system Hydraulic rotary drilling process Constant drilling speed Soil improvement Quality assessment

STUDY ON THE MECHANISM OF GRAPHITIzATION IN MOLTEN CAST IRON PROMOTED BY ELECTROPULSE DISCHARGE

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 790-794页

作者： G.W.Chang j.S.wang j.z.wang Q.G.Xue O.Q.zhou D.Q.Cang Dept.Materials＆ChemicalEng. LiaoningInstituteofTechnologyJinzhou121001China SchoolofMetallurgy BeijingUniversityofScience＆Technology.Beijing100083China

From the points of both molten cast iron structure and the appearing ratio of electrons in outer-layer of different atoms, analysis on enhancement mechanism of graphitization ability after processing of the iron by pulse electric discharge has been made, and the theory has been proofed by corresponding experiments. The results show that when the molten cast iron is being processed by pulse electric discharge, both the size of crystal embryos that composed by Fe and C atoms as well as the number of clusters can be reduced, even be separated by such discharging; consequently results in the segre- gation of C atoms in the molten cast iron near the cathode of discharging. The nucleation of graphite in these areas of the iron has been promoted at the discharging temperature; even though such degree has not been reached, the most favorable nucleation conditions of graphite can be at least created. Under the preconditions of not breaking up the graphite crystal embryos, with proper adjustment of discharging frequency, the stronger of the electric field and the longer of the pulsation treatment time are, the more graphitization ability of the molten cast iron is. The theoretical analysis on the above rules consists well with experimental results.

关键词： pulsed electric field molten iron-solution graphitization

A new scale for optimized cryogenic magnetocaloric effect in ErAl_2@Al_2O_3 nanocapsules

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journal of Materials Science & Technology 2018年第5期34卷 848-854页

作者： F.Wei S.Ma L.Yang Y.Feng j.z.wang A.Hua X.G.zhao D.Y.Geng z.D.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

The Er Al2@Al2O3 nanocapsules with Er Al2core and Al2O3 shell were synthesized by modified arc-charge *** typical core-shell structure of the nanocapsules was confirmed by high resolution transmission electron microscopy and X-ray photoelectron *** electron microscopy analysis shows the irregular sphere of the nanocapules with an average diameter of 26 *** investigation revealed the Curie temperature of Er Al2@Al2O3 nanocapsules at 20 K and the typical superparamagnetic behavior between blocking temperature and Curie *** on the blocking temperature and average diameter,the magnetocrystalline anisotropy constant of Er Al2@Al2O3nanocapsules was estimated to illustrate the magnetic contribution to *** large-SMof 14.25 j/（kg K）was obtained under 50 k Oe at 5 K.A vital parameter β was introduced in the present work to scale the optimized magnetic characteristics and the optimized mechanism was discussed in detail according to classical superparamagnetic *** results demonstrate that the optimal-SMwill be obtained when the magnetic parameter β is close to the theoretical coefficient.

关键词： Nanocapsules Magnetocaloric effect Superparamagnetic property Cryogenic refrigeration

Molecular beam epitaxy growth of monolayer hexagonal MnTe_(2)on Si(111)substrate

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Chinese Physics B 2021年第12期30卷 142-147页

作者： S Lu K Peng P D wang A X Chen W Ren X W Fang Y Wu z Y Li H F Li F Y Cheng K L Xiong j Y Yang j z wang S A Ding Y P jiang) L wang Q Li F S Li L F Chi Institute of Functional Nano&Soft Materials(FUNSOM) Soochow UniversitySuzhou 215123China Vacuum Interconnected Nanotech Workstation(Nano-X) Suzhou Institute of Nano-Tech and Nano-Bionics(SINANO)Chinese Academy of Sciences(CAS)Suzhou 215123China Key Laboratory of Polar Materials and Devices(MOE) Department of ElectronicSchool of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China School of Physical Science and Technology Southwest UniversityChongqing 400715China School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefei 230026China

Monolayer MnTe_(2)stabilized as 1 T structure has been theoretically predicted to be a two-dimensional(2 D)ferromagnetic metal and can be tuned via strain *** is no naturally van der Waals(vdW)layered MnTe_(2)bulk,leaving mechanical exfoliation impossible to prepare monolayer MnTe_(2).Herein,by means of molecular beam epitaxy(MBE),we successfully prepared monolayer hexagonal MnTe_(2)on Si(111)under Te rich *** reflection high-energy electron diffraction(RHEED)and low-energy electron diffraction(LEED)patterns suggest the monolayer is atomically flat without surface *** valence state of Mn^(4+)and the atom ratio of([Te]:[Mn])further confirm the MnTe_(2)*** tunneling spectroscopy(STS)shows the hexagonal MnTe_(2)monolayer is a semiconductor with a large bandgap of~2.78 *** valence-band maximum(VBM)locates at theΓpoint,as illustrated by angle-resolved photoemission spectroscopy(ARPES),below which three hole-type bands with parabolic dispersion can be *** successful synthesis of monolayer MnTe_(2)film provides a new platform to investigate the 2D magnetism.

关键词： molecular beam epitaxy hexagonal MnTe_(2) band structure

Compressive property and energy absorption characteristic of interconnected porous Mg-zn-Y alloys with adjusting Y addition

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journal of Magnesium and Alloys 2024年第1期12卷 171-185页

作者： j.A.Liu S.j.Liu B.wang W.B.Sun X.j.Liu z.W.Han College of Materials Science and Engineering Key Laboratory of Automobile Materials(Ministry of Education)Jilin UniversityChangchun 130022PR China Key Laboratory of Bionic Engineering(Ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchun130022PR China Weihai Institute for Bionics-jilin University Weihai 264205PR China

In this study,interconnected porous Mg-2zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption *** characterization methods were then applied to identify the microstructure of the porous Mg-zn-Y and describe the details of the second *** tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous *** experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second *** the Y content increases,different Mg-zn-Y ternary phases appear:I-phase(Mg_(3)zn_(6)Y),W-phase(Mg_(3)zn_(3)Y_(2)),and LPSO phase(Mg_(12)znY).When the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30MPa to 9.23 MPa,and the energy absorption capacity increases from 7.33 Mj/m^(3)to 10.97 Mj/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second ***,the average energy absorption efficiency is independent of the Y *** addition,the compressive deformation behaviors of the porous Mg-zn-Y are altered by the testing *** compressive strength and energy absorption capacity of the porous Mg-zn-Y decrease due to the softening effect of the high temperature on the *** deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.

关键词： Porous magnesium Rare earth elements Microstructure Compressive behavior Energy absorption characteristic

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.

Probing the Bardeen-Kiselev black hole with the cosmological constant caused by Einstein equations coupled with nonlinear electrodynamics using quasinormal modes and greybody bounds

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Communications in Theoretical Physics 2024年第6期76卷 102-119页

作者： S R Wu B Q wang z W Long College of Physics Guizhou UniversityGuiyang 550025China College Pharmacy Guizhou University of Traditional Chinese MedicineGuiyang 550025China

In this work,we investigate a static and spherically symmetric Bardeen-Kiselev black hole(BH)with the cosmological constant,which is a solution of the Einstein-non-linear Maxwell field *** compute the quasinormal frequencies for the Bardeen-Kiselev BH with the cosmological constant due to electromagnetic and gravitational *** varying the BH parameters,we discuss the behavior of both real and imaginary parts of the BH quasinormal frequencies and compare these frequencies with the Reissner-Nordström-de Sitter BH surrounded by quintessence(RN-dSQ).Interestingly,it is shown that the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dSQ under electromagnetic perturbations are different when the charge parameter q,the state parameter w and the normalization factor c are varied;however,for the gravitational perturbations,the responses of the Bardeen-Kiselev BH with the cosmological constant and the RN-dSQ are different only when the charge parameter q is ***,compared with the gravitational perturbations,the electromagnetic perturbations can be used to understand nonlinear and linear electromagnetic fields in curved spacetime *** interesting observation is that,due to the presence of Kiselev quintessence,the electromagnetic perturbations around the Bardeen-Kiselev BH with the cosmological constant damps faster and oscillates slowly;for the gravitational perturbations,the quasinormal mode decays slowly and oscillates *** also study the reflection and transmission coefficients along with the absorption cross section in the Bardeen-Kiselev BH with the cosmological constant;it is shown that the transmission coefficients will increase due to the presence of Kiselev quintessence.

关键词： quasinormal modes greybody factors Bardeen-Kiselev black hole with cosmological constant