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On the material constants measurement method of a fluid-saturated transversely isotropic poroelastic medium

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Science China(Physics,Mechanics & Astronomy) 2019年第1期62卷 69-75页

作者： Yue Gao ZhanLi Liu Zhuo Zhuang Keh-Chih Hwang AML Department of Engineering Mechanics Tsinghua University Center for Mechanics and Materials Tsinghua University

The fluid-saturated transversely isotropic poroelastic medium could be widely found in nature, e.g., the sedimentary rocks underground. To determine the eight independent material constants for the transversely isotropic poroelastic medium, a series of tests are discussed. Two undrained tests and one drained test are suggested as a set of tests of the least amount. For the verification purpose, two additional drained tests are also introduced as an option. The atmospheric dried test is discussed as a replacement of the traditional infiltrated drained test to save the time waiting for an equilibrium state. Some microscopic material constants, i.e.,the unjacketed bulk coefficients, the porosity, and the compressibility of porous fluid, are measurable but unnecessary to determine the independent material constants of a poroelastic medium.

关键词： poroelastic constitutive model material constants measurement transversely isotropic medium

Preparation and characterization of high softening point and homogeneous isotropic pitches produced from distilled ethylene tar by a novel bromination method

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新型炭材料 2018年第1期33卷 97-100页

作者： Chuan-zhang Ge Zhen-long Sun Hai-xiao Yang Dong-hui Long Wen-ming Qiao Li-cheng Ling State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China Shanghai Key Laboratory of Multiphase Materials Chemical Engineering East China University of Science and TechnologyShanghai 200237China

摘要: 以乙烯渣油减压蒸馏重组分（ET-HR）为原料，采用溴化/脱溴聚合两步法制备了新型高软化点各向同性沥青，研究了溴化温度和溴引入量对所得产品性质参数的影响。GCMS与LDI TOF/MS测试结果表明，ET-HR主要由富含饱和脂肪侧链的3-6环... 详细信息

摘要: 以乙烯渣油减压蒸馏重组分（ET-HR）为原料，采用溴化/脱溴聚合两步法制备了新型高软化点各向同性沥青，研究了溴化温度和溴引入量对所得产品性质参数的影响。GCMS与LDI TOF/MS测试结果表明，ET-HR主要由富含饱和脂肪侧链的3-6环芳香烃组成。ET-HR分别经30℃和200℃溴化后直接经350℃热处理发生脱溴化氢缩合反应。与简单热缩聚相比，该两步法显著提高了所得沥青的软化点（241~264℃）、产品得率（62 wt.%~67 wt.%）以及氮气下的残碳率（57 wt.%~77 wt.%）。对所得脱溴聚合沥青的组成和结构通过元素分析、 1H NMR、FT-IR和LDI-TOF/MS等技术手段进行了表征，结果表明脱溴聚合显著增强了前驱体的芳构化和缩聚反应程度。800℃炭化结果表明，溴化/脱溴聚合两步法所得各向同性沥青能够完全转变为各向异性织构，从而可广泛应用于高级炭材料领域。

关键词： high softening point and homogeneous isotropic pitches produced from distilled ethylene tar romination method

Applying resolved-scale linearly forced isotropic turbulence in rational subgrid-scale modeling

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Acta Mechanica Sinica 2019年第3期35卷 486-494页

作者： Chuhan Wang Mingwei Ge School of Renewable Energy North China Electric Power UniversityBeijing 102206China LMP Ecole Centrale de PékinBeihang UniversityBeijing 100191China

In previous attempts of rational subgrid-scale (SGS) modeling by employing the Kolmogorov equation of filtered (KEF) quantities, it was necessary to assume that the resolved-scale second-order structure function is stationary. Forced isotropic turbulence is often used as a framework for establishing and validating such SGS models based on stationary restrictions, for it generates statistical stationary samples. However, traditional forcing method at low wavenumbers cannot provide an analytic form of forcing term for a complete KEF in physical space, which has been illustrated to be essential in the modeling of such SGS models. Thus, an alternative forcing method giving an analytic forcing term in physical space is needed for rational SGS modeling. Giving an analytic linear driving term in physical space, linearly forced isotropic turbulence should be considered an ideal theoretical framework for rational SGS modeling. In this paper, we demonstrate the feasibility of establishing a rational SGS model with stationary restriction based on linearly forced isotropic turbulence. The performance of this rational SGS model is validated. We, therefore, propose the use of linearly forced isotropic turbulence as a complement to free-decaying isotropic turbulence and low-wavenumber forced isotropic turbulence for SGS model validations.

关键词： Homogeneous isotropic turbulence Large-eddy simulation Subgrid-scale model Forced turbulence

Stochastic modeling of subgrid-scale effects on particle motion in forced isotropic turbulence

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Chinese Journal of Chemical Engineering 2019年第12期27卷 2884-2891页

作者： Haoshu Shen YuxinWu Minmin Zhou Hai Zhang Guangxi Yue Key Laboratory for Thermal Science and Power Engineering of Ministry Education Department of Energy and Power EngineeringTsinghua UniversityBeijing 100084China Institute for Clean and Secure Energy Department of Chemical EngineeringUniversity of UtahSalt Lake City 84112United States

The subgrid-scale effects on particle motion were investigated in forced isotropic turbulence by DNS and priorLES methods.In the DNS field,the importance of Kolmogorov scaling to preferential accumulation was validated by comparing the radial distribution functions under various particle Stokes numbers.The prior-LES fields were generated by filtering the DNS data.The subgrid-scale Stokes number(StSGS)is a useful tool for determining the effects of subgrid-scale eddies on particle motion.The subgrid-scale eddies tend to accumulate particles with StSGSb 1 and disperse particles with 1 b StSGSb 10.For particles with StSGS?1,the effects of subgrid-scale eddies on particle motion can be neglected.In order to restore the subgrid-scale effects,the Langevin-type stochastic model with optimized parameters was adopted in this study.This model is effective for the particles with StSGS N 1 while has an adverse impact on the particles with StSGSb 1.The results show that the Langevin-type stochastic model tends to smooth the particle distribution in the isotropic turbulence.

关键词： Particle dispersion Subgrid-scale modeling Forced isotropic turbulence Stokes number

Plane Vibrations in a Transversely isotropic Infinite Hollow Cylinder Under Effect of the Rotation and Magnetic Field

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Computer Modeling in Engineering & Sciences 2017年第2期113卷 151-170页

作者： F.S.Bayones A.M.Abd-Alla Math.Dept. Faculty of ScienceTaif UniversitySaudi Arabia Mathematics Department Faculty of ScienceSohagEgypt

The aim of this paper is to study the effects of rotation and magnetic field on the plane vibrations in a transversely isotropic material of an infinite hollow cylinder.The natural frequency of the plane vibrations in the case of harmonic vibrations has been obtained.The natural frequencies are calculated numerically and the effects of rotation and magnetic field are discussed.The numerical results obtained have been illustrated graphically to understand the behavior of frequency equation with different values of frequencyωunder effects the rotation and magnetic field.Comparison was made with the results obtained in the presence and absence of the rotation and magnetic field.The results indicate that the effect of rotation and magnetic field are very pronounced.

关键词： Plane transversely isotropic rotating magnetic field homogeneous transversely isotropic Natural frequencies

Direct numerical simulation of compressible isotropic turbulence

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Science China Mathematics 2002年第11期45卷 1452-1460页

作者：李新亮傅德薰马延文 LNM Institute of Mechanics Chinese Academy of Sciences Beijing China LHD Institute of Mechanics Chinese Academy of Sciences Beijing China

Direct numerical simulation (DNS) of decaying compressible isotropic turbulence at tur-bulence Mach numbers of Mt = 0.2-0.7 and Taylor Reynolds numbers of 72 and 153 is per-formed by using the 7th order upwind-biased difference and 8th order center difference schemes.Results show that proper upwind-biased difference schemes can release the limit of 'start-up'problem to Mach numbers.Compressibility effects on the statistics of turbulent flow as well as the mechanics of shockletsin compressible turbulence are also studied, and the conclusion is drawn that high Mach numberleads to more dissipation. Scaling laws in compressible turbulence are also analyzed. Evidence isobtained that scaling laws and extended self similarity (ESS) hold in the compressible turbulentflow in spite of the presence of shocklets, and compressibility has little effect on scaling exponents.

关键词： direct numerical simulation, isotropic turbulence, compressibility effect, scaling law.

A chiral SrSi_(2)(srs)superstructure constructed by a dual interaction system showing isotropic electrical conductivity

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中国化学快报:英文版 2023年第9期34卷 317-320页

作者： Jin Liu Zi-Xiu Lu Fa-Fa Wu Guo-Ling Li Bin Wang Xue-Li Cao Wei Wang Zhu Zhuo Qiao-Hong Li You-Gui Huang CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstitutesChinese Academy of SciencesXiamen 361021China State Key Laboratory of Structure Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

Most porous conductive frameworks are highly anisotropic in their structures thus leading to anisotropic charge transport.Here we report a supramolecular self-assembly which is constructed by intermolecular hydrogen bonding andπ···πinteractions.This material features a chiral,porous,cubic framework structure withπ-stacked helical columns along all of the three Cartesian coordinates.As a result,isotropic charge transport with an electrical conductivity(σ)of 2.1×10^(–7)S/cm is achieved.By achieving isotropic charge transport in aπ-stacked supramolecular assembly,these results provide a new type of isotropic conductive framework materials alternative to conductive metal-organic frameworks(MOFs).

关键词： Electrical conductivity Self-assembly isotropic π···πInteractions Chiral

Fundamental solutions for transversely isotropic magneto-electro-elastic media and boundary integral formulation

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Science China(Technological Sciences) 2003年第6期46卷 607-619页

作者：丁皓江江爱民 Department of Civil Engineering Zhejiang University Hangzhou 310027 China West Branch of Zhejiang University of Technology Quzhou 324006 China

To obtain the fundamental solutions for computation of magneto-electro-elastic media by the boundary element method, the general solutions in the case of distinct eigenvalues are de-rived and expressed in five harmonic functions from the governing equations and the strict differ-ential operator theorem. On the basis of these general solutions, the fundamental solution of infi-nite magneto-electro-elastic solid are obtained with the method of trial-and-error. Finally, the boundary integral formulation is derived and the corresponding boundary element method program is implemented to perform two numerical calculations(a column under uni-axial tension, uniform electric displacement or uniform magnetic induction, an annular plate simply-supported on outer and inner surfaces under axial loads). The numerical results agree well with the analytical ones.

关键词： transversely isotropic magneto-electro-elastic media, fundamental solution, boundary integral formulation.

Fabrication of metal suspending nanostructures by nanoimprint lithography(NIL) and isotropic reactive ion etching(RIE)

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Science China(Technological Sciences) 2009年第5期52卷 1181-1186页

作者： XIE GuoYong ZHANG Jin ZHANG YongYi ZHANG YingYing ZHU Tao LIU ZhongFan Center for Nanoscale Science and Technology(CNST) College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Nanotechnology Industrialization Base of China Tianjin 300457China

We report herein a rational approach for fabricating metal suspending nanostructures by nanoimprint lithography(NIL) and isotropic reactive ion etching(RIE).The approach comprises three principal steps:(1) mold fabrication,(2) structure replication by NIL,and(3) suspending nanostructures creation by isotropic RIE.Using this approach,suspending nanostructures with Au,Au/Ti or Ti/Au bilayers,and Au/Ti/Au sandwiched structures are demonstrated.For Au nanostructures,straight suspending nanostructures can be obtained when the thickness of Au film is up to 50 nm for nano-bridge and 90 nm for nano-finger patterns.When the thickness of Au is below 50 nm for nano-bridge and 90 nm for nano-finger,the Au suspending nanostructures bend upward as a result of the mismatch of thermal expansion between the thin Au films and Si substrate.This leads to residual stresses in the thin Au films.For Au/Ti or Ti/Au bilayers nanostructures,the cantilevers bend toward Au film,since Au has a larger thermal expansion coefficient than that of Ti.While in the case of sandwich structures,straight suspending nanostructures are obtained,this may be due to the balance of residual stress between the thin films.

关键词： suspending nanostructure fabrication nanoimprint lithography(NIL) isotropic reactive ion etching(RIE)