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Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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Science China(physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： PENG Miaojuan1 & XU Zhihong2.1. Department of Civil Engineering,shanghai university,shanghai 2.0072.China 2. School of Transportation Engineering,Tongji university,shanghai 2.0092.China 1. Department of Civil Engineering Shanghai University Shanghai 200072 China 2. School of Transportation Engineering Tongji University Shanghai 200092 China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

Study on the bulk wave radiation of finite-length SAW devices using FEM/BEM

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Progress in Natural Science:Materials International 2005年第5期15卷 402-406页

作者： WANG Weibiao1*, ZHANG Xiaodong1, SHUI Yongan1, ZHANG De1 and HAN Tao2.1. State Key laboratory of Modern Acoustics, Institute of Acoustics, Nanjing university, Nanjing 2.0093, China 2. {2. Jiaotong university, {2. 2.0030, China) State Key laboratory of Modern Acoustics Institute of Acoustics Nanjing University Nanjing 210093 China shanghai Jiaotong university Shanghai 200030 China

Based on the distributions of stress and free charge on the interface of the surface acoustic wave (SAW) device calculated with the combination of boundary element method and finite element method(FEM/BEM), the power of each of the three possible bulk waves radiated by the SAW device is calculated, and their contributions to the overall input conductance are separated respectively. Moreover, the formula of angular distributions of their power radiation into the substrate is derived. Consider the effect of mass loading, the resistance density,defined as a scalar, is extended to generalized resistance densities which can be written as three 4×4 tensors and for which the formulas are derived. The bulk wave radiations for a synchronous one-port resonator on 42.Y-rotated LiTaO 3 are simulated. It is found that the radiated energy by slow shear wave contributes a very high proportion to input electrical energy in some frequency range.

关键词： SAW device bulk wave radiation FEM/BEM.

TURNING-OVER OF THE ELECTRIC DIPOLE IN A POLYMER

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Chinese Journal of Polymer Science 2001年第6期19卷 573-578页

作者： Guang-qi Li Xin Sun and Sheng Li State Key laboratory of surface {2. and Research Center for Theoretical {2., fudan university shanghai 2.0433, China National laboratory of Infrared {2., shanghai Institute of Technical {2.,shanghai 2.0083, China fudan Univ State Key Lab Surface Phys Shanghai 200433 Peoples R China fudan Univ Res Ctr Theoret Phys Shanghai 200433 Peoples R China Acad Sinica Shanghai Inst Tech Phys Natl Lab Infrared Phys Shanghai 200083 Peoples R China

The transition from the biexciton to the exciton can turn over the direction of the electric dipole of a polymericmolecule. This turning-over action combined with the photoinduced polarization reversion can be used as a switch. Theswitching speed is governed by the relaxation time of the turning-over process, which can be determined by a dynamicalsimulation.

关键词： exciton biexciton electric dipole switch relaxation

A complex variable meshless method for fracture problems

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Science China(physics,Mechanics & Astronomy) 2006年第1期49卷 46-59页

作者： CHENG Yumin1 & LI Jiuhong2.1. shanghai Institute of Applied Mathematics and Mechanics, shanghai {2., shanghai 2.0072. China 2. Department of Building Engineering, Xi’an {2. of Technology, Xi’an 710048, China shanghai Institute of Applied Mathematics Mechanics Shanghai University Shanghai 200072 China Department of Building Engineering Xi’an University of Technology Xi’an 710048 China

Based on the moving least-square (MLS) approximation, the complex variable moving least-square approximation (CVMLS) is discussed in this paper. The complex variable moving least-square approximation cannot form ill-conditioned equations, and has greater precision and computational efficiency. Using the analytical solution near the tip of a crack, the trial functions in the complex variable moving least-square approxi- mation are extended, and the corresponding approximation function is obtained. And from the minimum potential energy principle, a complex variable meshless method for fracture problems is presented, and the formulae of the complex variable meshless method are obtained. The complex variable meshless method in this paper has greater precision and computational efficiency than the conventional meshless method. Some examples are given.

关键词： moving least-square approximation, complex variable moving least-square approximation, meshless method, complex variable meshless method, fracture.

Superconductivity of small metal grains

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Science China(physics,Mechanics & Astronomy) 2005年第4期48卷 431-441页

作者： ZHENG Renrong1 CHEN Zhiqian2.& ZHU Shunquan1,3 1. Department of physics, shanghai Normal {2., shanghai 2.02.4, China 2. Department of physics, Southwest Normal {2., Chongqing 400715, China 3. Department of Computer and Electric Technology, shanghai Business School, shanghai 2.1400, China 1. Department of physics Shanghai Normal University 200234 Shanghai China 2. Department of physics Southwest Normal University 400715 Chongqing China 3. Department of Computer and Electric Technology Shanghai Business School 201400 Shanghai China

The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

关键词： size effect, superconductivity enhancements, small metallic grains.

Preparation and Microstructure of Spinel Zinc Ferrite ZnFe_2._4 by Co-precipitation Method

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Journal of Wuhan university of Technology(Materials Science) 2009年第6期24卷 927-930页

作者：任平 Department of Energy Sources and Environment Engineering Shanghai University of Electric Power

Spinel zinc ferrites ZnFe2.4, prepared by co-precipitation method using the zinc nitrate Zn（NO3）2.6H2. and ferric nitrate Fe（NO3）3·2.2. as the raw materials, were characterized by the thermo gravimetric analysis （TG） and differential scanning calorimeter （DSC）, X-ray diffraction （XRD） and scanning electron microscope （SEM）. The influence of synthesis conditions, such as Zn/Fe molar ratio, pH value, the sintering temperature and time, on the microstructures was detailedly investigated. The relationships between the microstructures and the synthesis conditions were discussed. The results show that the pure spinel zinc ferrites ZnFe2.4 are formed when the Zn/Fe molar ratio is 1.05∶2.at pH=8.5 or Zn/Fe molar ratio is 1∶2.at Ph=9-10, and the precursors are sintered at 1100 ℃ for 4 h. Especially no other phases are observed when the Zn/Fe molar ratio is 1∶2.at pH=10 and the precursor is sintered above 700 ℃ for 4 h. The higher sintering temperature and longer sintering time contribute to grain growth.

关键词： zinc ferrites ZnFe2.4 microstructures co-precipitation

A pulse radiolysis study on electron affinity of piperonal

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Science China Chemistry 2005年第5期48卷 476-480页

作者： MA Jianhua1, LIN Weizhen2. WANG Wenfeng2.& YAO Side2.1. College of Biology Engineering, Jimei university, Xiamen 36102., China 2. shanghai Institute of Applied {2., Chinese Academy of Sciences, shanghai 2.1800, China 1. College of Biology Engineering Jimei University 361021 Xiamen China 2. shanghai Institute of Applied physics Chinese Academy of Sciences 201800 Shanghai China

The piperonal electron affinity was studied using pulse radiolysis technique. The electron transfer reaction process between piperonal and anthraquinone-2.sulfate was observed in the pH 7 phosphoric acid salt buffer. The transient absorption spectra of electron transfer re-action between piperonal and anthraquinone-2.sulfate were obtained, and the initial proof of the electron transfer between electron donor and acceptor was provided directly. The one-electron reduction potential of piperonal was determined to be ?0.457 V.

关键词： piperonal, pulse radiolysis, one-electron reduction potential.

CMC surfaces in the hyperbolic 3-space

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Chinese Science Bulletin 1998年第7期43卷 547-550页

作者： YU Zuhuan 1, 2.and LI Zhenqi 1, 3 1. Institute of Mathematics, fudan university, shanghai 2.0433, China 2. Department of Mathematics,Sichuan Union {2., Chengdu 610064, China 3. Department of Mathematics, Nanchang {2., Nanchang 33 nstitute of Mathemalics Fudan University Shanghai China Department of Mathematics Sichuan Union University Chengdu China Department of Mathematics Nanchang University Nanchang China

CMC-H surfaces satisfying H≥1 are studied. It is proved that these surfaces possess a natural representation which is a generalization of the Bryant’s result.

关键词： hyperbolic space CMC surface Weierstrass representation.

A phenomenological equation of state for isospin asymmetric nuclear matter

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Science China(physics,Mechanics & Astronomy) 2009年第10期52卷 1494-1505页

作者： CHEN LieWen1,2.1 Department of physics,shanghai Jiao Tong {2.,shanghai 2.02.0,China 2.Center of Theoretical Nuclear physics,National laboratory of Heavy Ion Accelerator,Lanzhou 730000,China Department of physics Shanghai Jiao Tong University Shanghai 200240 China Center of Theoretical Nuclear physics National Laboratory of Heavy Ion Accelerator Lanzhou 730000 China

A phenomenological momentum-independent(MID) model is constructed to describe the equation of state(EOS) for isospin asymmetric nuclear matter,especially the density dependence of the nuclear symmetry energy Esym(ρ).This model can reasonably describe the general properties of the EOS for symmetric nuclear matter and the symmetry energy predicted by both the sophisticated isospin and momentum dependent MDI model and the Skyrme-Hartree-Fock *** find that there exists a nicely linear correlation between Ksym and L as well as between J0/K0 and K0,where L and Ksym represent,respectively,the slope and curvature parameters of the symmetry energy at the normal nuclear density ρ0,while K0 and J0 are,respectively,the incompressibility and the third-order derivative parameter of symmetric nuclear matter at ρ*** correlations together with the empirical constraints on K0,L and Esym(ρ0) lead to an estimation of -477 MeV Ksat,2.-2.1 MeV for the second-order isospin asymmetry expansion coefficient for the incompressibility of asymmetric nuclear matter at the saturation point.

关键词： equation of state of nuclear matter isospin the symmetry energy