A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is ob...A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is obtained through the complex potential approach in conjunction with the techniques of analytical continuation, singularity analysis, Laurent series expansion in an annular region and Cauchy integral formulae, etc. Based on the complex potentials obtained, explicit expressions for the distribution of stress and electric displacement in the three regions are also derived.展开更多
An in-depth investigation is made on the problem of an arc-shapedinterface insulating crack in a three-phase concentric circularcylindrical piezoelectric composite constitutive model. An exactsolution in series form i...An in-depth investigation is made on the problem of an arc-shapedinterface insulating crack in a three-phase concentric circularcylindrical piezoelectric composite constitutive model. An exactsolution in series form is derived by employing the complex variablemethod. In addition, the distribution of physical quantities such asstresses, strains, electric displacements and electric fields in thewhole field and along the interface is also presented.展开更多
The present work is devoted to the determination of linear effective thermal conductivity of porous rocks characterized by an assemblage of grains(oolites) coated by a matrix. Two distinct classes of pores, i.e.microp...The present work is devoted to the determination of linear effective thermal conductivity of porous rocks characterized by an assemblage of grains(oolites) coated by a matrix. Two distinct classes of pores, i.e.micropores or intra oolitic pores(oolite porosity) and mesopores or inter oolitic pores(inter oolite porosity), are taken into account. The overall porosity is supposed to be connected and decomposed into oolite porosity and matrix porosity. Within the framework of Hashin composite sphere assemblage(CSA)models, a two-step homogenization method is developed. At the first homogenization step, pores are assembled into two layers by using self-consistent scheme(SCS). At the second step, the two porous layers constituting the oolites and the matrix are assembled by using generalized self-consistent scheme(GSCS) and referred to as three-phase model. Numerical results are presented for data representative of a porous oolitic limestone. It is shown that the influence of porosity on the overall thermal conductivity of such materials may be significant.展开更多
N-layered spherical inclusions model was used to calculate the effective diffusion coefficient of chloride ion in cement-based materials by using multi-scale method and then to investigate the relationship between the...N-layered spherical inclusions model was used to calculate the effective diffusion coefficient of chloride ion in cement-based materials by using multi-scale method and then to investigate the relationship between the diffusivity and the microstructure of cement-basted materials where the microstructure included the interfacial transition zone （ITZ） between the aggregates and the bulk cement pastes as well as the microstructure of the bulk cement paste itself. For the convenience of applications, the mortar and concrete were considered as a four-phase spherical model, consisting of cement continuous phase, dispersed aggregates phase, interface transition zone and their homogenized effective medium phase. A general effective medium equation was established to calculate the diffusion coefficient of the hardened cement paste by considering the microstructure. During calculation, the tortuosity （n） and constrictivity factors （Ds/Do） of pore in the hardened pastes are n^3.2, Ds/Do=l.Ox 10-4 respectively from the test data. The calculated results using the n-layered spherical inclusions model are in good agreement with the experimental results; The effective diffusion coefficient of ITZ is 12 times that of the bulk cement for mortar and 17 times for concrete due to the difference between particle size distribution and the volume fraction of aggregates in mortar and concrete.展开更多
A local composition expression has been derived from the Guggenheim′s quasi-chemicalequation.On this basic a thermodynamic model,the quasi-chemical local composition model(QCLC)was established.To examine its capabili...A local composition expression has been derived from the Guggenheim′s quasi-chemicalequation.On this basic a thermodynamic model,the quasi-chemical local composition model(QCLC)was established.To examine its capability for correlation and prediction,Baxter′s adhesivehard sphere mixtures were used,and an improved numerical method was proposed to estimate theirthermodynamic properties.By means of this method the excess properties of the mixtures composedof four kinds of adhesive hard spheres were calculated,The activity coefficients from QCLC modelwere compared with those from the Wilson,NRTL and UNIQUAC equations.Results show thatamong these models,the QCLC model is the best one for correlation and prediction.展开更多
Composite load model of Western Electricity Coordinating Council(WECC)is a newly developed load model that has drawn great interest from the industry.To analyze its dynamic characteristics with both mathematical and e...Composite load model of Western Electricity Coordinating Council(WECC)is a newly developed load model that has drawn great interest from the industry.To analyze its dynamic characteristics with both mathematical and engineering rigors,a detailed mathematical model is needed.Although composite load model of WECC is available in commercial software as a module and its detailed block diagrams can be found in several public reports,there is no complete mathematical representation of the full model in literature.This paper addresses a challenging problem of deriving detailed mathematical representation of composite load model of WECC from its block diagrams.In particular,we have derived the mathematical representation of the new DERA model.The developed mathematical model is verified using both MATLAB and PSS/E to show its effectiveness in representing composite load model of WECC.The derived mathematical representation serves as an important foundation for parameter identification,order reduction and other dynamic analysis.展开更多
文摘A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is obtained through the complex potential approach in conjunction with the techniques of analytical continuation, singularity analysis, Laurent series expansion in an annular region and Cauchy integral formulae, etc. Based on the complex potentials obtained, explicit expressions for the distribution of stress and electric displacement in the three regions are also derived.
基金the National Natural Science Foundation of China(No.59635140)the Doctorate Foundation of Xi'an Jiaotong University
文摘An in-depth investigation is made on the problem of an arc-shapedinterface insulating crack in a three-phase concentric circularcylindrical piezoelectric composite constitutive model. An exactsolution in series form is derived by employing the complex variablemethod. In addition, the distribution of physical quantities such asstresses, strains, electric displacements and electric fields in thewhole field and along the interface is also presented.
基金support from TAMER (Trans-Atlantic Micromechanics Evolving Research) European Project (materials containing inhomogeneities of diverse physical properties, shapes and orientations)FP7 Project TAMER IRSES-GA2013-610547
文摘The present work is devoted to the determination of linear effective thermal conductivity of porous rocks characterized by an assemblage of grains(oolites) coated by a matrix. Two distinct classes of pores, i.e.micropores or intra oolitic pores(oolite porosity) and mesopores or inter oolitic pores(inter oolite porosity), are taken into account. The overall porosity is supposed to be connected and decomposed into oolite porosity and matrix porosity. Within the framework of Hashin composite sphere assemblage(CSA)models, a two-step homogenization method is developed. At the first homogenization step, pores are assembled into two layers by using self-consistent scheme(SCS). At the second step, the two porous layers constituting the oolites and the matrix are assembled by using generalized self-consistent scheme(GSCS) and referred to as three-phase model. Numerical results are presented for data representative of a porous oolitic limestone. It is shown that the influence of porosity on the overall thermal conductivity of such materials may be significant.
基金Funded by the National Basic Research Program of China (No.2009CB623203)the National High-Tech R&D Program of China (No.2008AA030794)the Postgraduates Research Innovation in University of Jiangsu Province in China (No.CX10B-064Z)
文摘N-layered spherical inclusions model was used to calculate the effective diffusion coefficient of chloride ion in cement-based materials by using multi-scale method and then to investigate the relationship between the diffusivity and the microstructure of cement-basted materials where the microstructure included the interfacial transition zone （ITZ） between the aggregates and the bulk cement pastes as well as the microstructure of the bulk cement paste itself. For the convenience of applications, the mortar and concrete were considered as a four-phase spherical model, consisting of cement continuous phase, dispersed aggregates phase, interface transition zone and their homogenized effective medium phase. A general effective medium equation was established to calculate the diffusion coefficient of the hardened cement paste by considering the microstructure. During calculation, the tortuosity （n） and constrictivity factors （Ds/Do） of pore in the hardened pastes are n^3.2, Ds/Do=l.Ox 10-4 respectively from the test data. The calculated results using the n-layered spherical inclusions model are in good agreement with the experimental results; The effective diffusion coefficient of ITZ is 12 times that of the bulk cement for mortar and 17 times for concrete due to the difference between particle size distribution and the volume fraction of aggregates in mortar and concrete.
文摘A local composition expression has been derived from the Guggenheim′s quasi-chemicalequation.On this basic a thermodynamic model,the quasi-chemical local composition model(QCLC)was established.To examine its capability for correlation and prediction,Baxter′s adhesivehard sphere mixtures were used,and an improved numerical method was proposed to estimate theirthermodynamic properties.By means of this method the excess properties of the mixtures composedof four kinds of adhesive hard spheres were calculated,The activity coefficients from QCLC modelwere compared with those from the Wilson,NRTL and UNIQUAC equations.Results show thatamong these models,the QCLC model is the best one for correlation and prediction.
基金supported by the Power Systems Engineering Research Center(No.S-84G)
文摘Composite load model of Western Electricity Coordinating Council(WECC)is a newly developed load model that has drawn great interest from the industry.To analyze its dynamic characteristics with both mathematical and engineering rigors,a detailed mathematical model is needed.Although composite load model of WECC is available in commercial software as a module and its detailed block diagrams can be found in several public reports,there is no complete mathematical representation of the full model in literature.This paper addresses a challenging problem of deriving detailed mathematical representation of composite load model of WECC from its block diagrams.In particular,we have derived the mathematical representation of the new DERA model.The developed mathematical model is verified using both MATLAB and PSS/E to show its effectiveness in representing composite load model of WECC.The derived mathematical representation serves as an important foundation for parameter identification,order reduction and other dynamic analysis.
