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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 {2.,shanghai 2.0072.china 2. School of Transportation Engineering,tongji {2.,shanghai 2.0092.china Department of Civil Engineering Shanghai University Shanghai China School of Transportation Engineering Tongji University Shanghai 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.

Boundary element-free method for elastodynamics

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Science china(Physics,Mechanics & Astronomy) 2005年第6期48卷 641-657页

作者： CHENG Yumin1 & PENG Miaojuan2.1. shanghai Institute of Applied Mathematics and Mechanics, shanghai {2., shanghai 2.0072. china 2. Department of Civil Engineering, shanghai {2., shanghai 2.0072. china shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai China Department of Civil Engineering Shanghai University Shanghai China

The moving least-square approximation is discussed first. Sometimes the method can form an ill-conditioned equation system, and thus the solution cannot be obtained correctly. A Hilbert space is presented on which an orthogonal function system mixed a weight function is defined. Next the improved moving least-square approximation is discussed in detail. The improved method has higher computational efficiency and precision than the old method, and cannot form an ill-conditioned equation system. A boundary element-free method (BEFM) for elastodynamics problems is presented by combining the boundary integral equation method for elastodynamics and the improved moving least-square approximation. The boundary element-free method is a meshless method of boundary integral equation and is a direct numerical method compared with others, in which the basic unknowns are the real solutions of the nodal variables and the boundary conditions can be applied easily. The boundary element-free method has a higher computational efficiency and precision. In addition, the numerical procedure of the boundary element-free method for elastodynamics problems is presented in this paper. Finally, some numerical examples are given.

关键词： moving least-square approximation, improved moving least-square approximation, elastodynamics, boundary integral equation, meshless method, boundary element-free method, Fourier eigen transform.

Fracture analysis of a functionally graded interfacial zone between two dissimilar homogeneous materials

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Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 540-552页

作者： CHENG Zhanqi1,2.& ZHONG Zheng1 1. School of Aerospace Engineering and Applied mechanics, tongji university,{2. 2. College of Civil Engineering, Zhengzhou {2., Zhengzhou 450002. china School of Aerospace Engineering and Applied mechanics Tongji University Shanghai China College of Civil Engineering Zhengzhou University Zhengzhou China

In this paper the plane elasticity problem for a functionally graded interfacial zone containing a crack between two dissimilar homogeneous materials has been considered. It is assumed that in the interfacial zone the reciprocal of the shear modulus is a linear function of the coordinate, while Possion’s ratio keeps constant. By utilizing the Fourier transformation technique and the transfer matrix method, the mixed boundary problem is reduced to a system of singular integral equations that are solved numerically. The influences of the geometric parameters and the graded parameter on the stress intensity factors are investigated. The numerical results show that the graded parameters, the thickness of interfacial zone, the crack size and location have significant effects on the stress intensity factors.

关键词： functionally graded material interfacial zone fracture stress intensity factor

Paleoceanographic evolution recorded in the northern South china Sea since 4 Ma

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Science china Earth Sciences 2005年第12期48卷 2166-2173页

作者： HUANG Baoqi1,2. JIAN Zhimin2.& WANG Pinxian2.1. School of Earth and Space Sciences, Peking university, Beijing 100871, china 2. Laboratory of Marine Geology,{2., shanghai 2.0092. china School of Earth and Space Sciences Peking University Beijing China Laboratory of Marine Geology Tongji University Shanghai China

Upper water structure over the last 4 million years in the northern South china Sea (SCS) was reconstructed by sea surface temperature (SST) and primary productivity estimated by changes in the abundance of planktonic foraminifer, planktonic foraminifer transfer function, and the accumulation rate of benthic foraminifera. Results of SST and primary productivity show that SST gradually decreased since 4 Ma, but differential seasonal temperature and primary productivity increased in steps mainly at about 3.1, 2.7, 2.1, 1.6, 0.9 and 0.5 Ma. Comparison with tectonics and orbital variations indicates that phased rising of the Tibet since 3.6 Ma, closing of Panama and Indonesian seaways, and orbital changes were responsible for the changes of upper water structure in the SCS, respectively.

关键词： northern South china Sea, upper water structure, Late Pliocene, planktonic foraminifer, ODP 1146.

Explicit Analytical Solutions for the Shearingand Radial Stresses in Curved Beams

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Communications in Nonlinear Science and Numerical Simulation 1999年第2期4卷 151-156页

作者： Aiming YU+ Xiangrong LI+++ (tongji university,{{2.)++ (shanghai university, shanghai {2.007{2. china) tongji university Shanghai 200092 China shanghai university Shanghai 200072 China

The shearing stresses in curved beams can be solved explicitly from anintegral equation, which is obtained by differentiation & integral manipulations. Twonovel formulae for shearing & radial stresses are also presented in the paper. The resultsof an example reveal that the shearing & radial stresses arrive at their maximum valuesslightly below the centroid of the section.

关键词： curved beam shearing stress radial stress integral equation

Macro-micromechanical approaches for non-coaxiality of coarse grained soils

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中国科学：技术科学英文版 2011年第S1期54卷 147-153页

作者： QIAN JianGu 1,2.HUANG MaoSong 1,2.& SUN HaiZhong 1,2.1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,tongji university,{2. 2.0092.china 2.Department of Geotechnical Engineering,tongji university,{2. 2.0092.china Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai China Department of Geotechnical Engineering Tongji University Shanghai China

For coarse grained soils,their principal stress directions may change when the water level of embankment dam varies *** this loading case,the principal directions of stress and strain rate will become *** an effort to model non-coaxial behavior,a modified three-dimensional non-coaxial model is developed in the context of vertex yield(tangent plasticity) *** Element Method(PFC) incorporating user-defined interparticle contact models is also employed to gain an insight into microscopic mechanism of *** analysis focuses on non-coaxial behaviors under simple shear *** has been shown that the proposed non-coaxial model gives good predictions for non-coaxiality with reference to microscopic observations while the classical coaxial model fails to simulate the non-coaxial *** general,non-coaxiality as a result of the rotation of principal stress,is large at a small shear strain,and inclined to become negligible with increasing shear *** coarse grained soils,their non-coaxiality tends to largely depend on the initial normal pressure,where a larger degree of non-coaxiality can be observed at a higher pressure.

关键词： coarse grained soils non-coaxiality particle flow code simple shear

Regulation of EGF-induced ERK/MAPK Activation and EGFR Internalization by G Protein-coupled Receptor Kinase 2

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Acta Biochimica et Biophysica Sinica 2005年第8期37卷 525-531页

作者： Jingxia GAO~(1,2.) Jiali LI~1 Lan MA~(1*) ~1 Pharmacology Research Center,shanghai Medical College.Fudan {2.,shanghai 2.0032.china ~2.Department of Biochemistry Medical College,tongji {2.,shanghai 2.0092.china Pharmacology Research Center Shanghai Medical College Fudan UniversityShanghai 200032 China Department of Biochemistry Medical College Tongji UniversityShanghai 200092 China

G protein-coupled receptor kinases(GRKs)mediate agonist-induced phosphorylation anddesensitization of various G protein-coupled receptors(GPCRs).We investigate the role of GRK2.on epidermalgrowth factor(EGF)receptor signaling,including EGF-induced extracellular signal-regulated kinase andmitogen-activated protein kinase(ERK/MAPK)activation and EGFR *** immunofluorescence experiments show that EGF stimulates GRK2.binding to EGFR complex and GRK2.ranslocating from cytoplasm to the plasma membrane in human embryonic kidney 2.3 *** assay shows that EGF-induced ERK/MAPK phosphorylation increases 1.9-fold,1.1-fold and 1.5-fold(P2. min,respectively when the cells were transfected with GRK2.suggesting the regulatory role of GRK2.on EGF-induced ERK/MAPK *** cytometry experimentsshow that GRK2.overexpression has no effect on EGF-induced EGFR internalization,however,it increasesagonist-induced G protein-coupled δ opioid receptor internalization by approximately 40% (P2.has a regulatory role in EGF-induced ERK/MAPK activation,and that themechanisms underlying the modulatory role of GRK2.in EGFR and GPCR signaling pathways are somewhatdifferent at least in receptor internalization.

关键词： G protein-coupled receptor kinase receptor tyrosine kinase epidermal growth factor receptor ERK/MAPK internalization

Model test of the tunnel subjected to high water pressure in Jinping Second Cascade Hydropower Station,china

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Science china(Technological Sciences) 2011年第S1期54卷 192-198页

作者： WANG JianXiu 1,2.FENG Bo 2.HU LiSheng 2.TIAN PuZhuo 2.SUI DongChang 2.TANG YiQun 1,2.&YANG Ping 1,2.1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,tongji university,{2. 2.0092.china 2.Department of Geotechnical Engineering,tongji university,{2. 2.0092.china Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai China Department of Geotechnical Engineering Tongji University Shanghai China

In the area with high groundwater pressure,grout curtain is often adopted to reduce the water pressure on tunnel lining.A series of model tests for the diversion tunnel of the Jinping Second Cascade Hydropower Station,china,is designed to study the effect of grout *** impact of the thickness of grout curtain,permeability of grout curtain,internal water pressure and drainage inflow on the distribution of water pressure are *** results indicates that under un-drained condition,water pressure is equal to hydrostatic one no matter grout curtain is selected or not,water pressure under drained condition is far less than that of un-drained condition,drainage in tunnel can reduce tunnel water pressure *** same inflow,both increasing of thickness and decrease of hydraulic conductivity of grout curtain can reduce water pressure *** the same water pressure,the smaller inflow of grout curtain,the less volume of water to be *** impact of hydraulic conductivity of grout curtain is more obvious than that of *** increasing of internal water pressure,the water pressure of grout curtain increases too,and the water pressure increases nearly *** proposed thickness of grout curtain for the diversion tunnels is 16 m.

关键词： tunnel grout curtain water pressure model test

Population-size-dependent branching processes in Markovian random environments

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Chinese Science Bulletin 1998年第8期43卷 635-638页

作者： WANG Hanxing 1 and DAI Yonglong 2.1. Department of Mathematics, shanghai {2., shanghai 2.1800, china 2. Department of Mathematics, Zhongshan {2., Guangzhou 5102.5, china Department of Mathematics Shanghai University Shanghai China Department of Mathematics Zhongshan University Gunngzhou China

A branching model {Z n} n≥0is considered where the offspring distribution of the population’s evolution is not only dependent on the population size, but also controlled by a Markovian environmental process {ξ n} n≥0. For this model, asymptotic behaviour is studied such as limn→∞Z n and limn→∞Z n/m n in the case that the mean m k, θof the offspring distribution converges to m>1 as the population size k grows to ∞. In the case that {ξ n} n≥0is an irreducible positive recurrent Markov chain, certain extinction (i.e. P(Z n=0 for some n)=1) and noncertain extinction (i.e. P(Z n=0 for some n)<1) are studied.

关键词： Markov chains in random environments stochastic population models branching processes.