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Based on a first-principles approach,we establish an alternating-current(AC) relaxation theory for a rotating metallic particle with complex dielectric constant ε_α=ε_α-iσ_α/ω_0.Here εα is the real part,σ_α the conductivity,ω_0 the angular frequency of an AC electric field,and i=-1~(1/2).Our theory yields an accurate interparticle force,which is in good agreement with the existing experiment.The agreement helps to show that the relaxations of two kinds of charges,namely,surface polarized charges(described by ε_α) and free charges(corresponding to σ_α),contribute to the unusually large reduction in the attracting interparticle force.This theory can be adopted to determine the relaxation time of dynamic particles in various fields. 相似文献
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Effective elastic properties of spherically anisotropic piezoelectric composites, whose spherically anisotropic piezo-electric inclusions are embedded in an infinite non-piezoelectric matrix, are theoretically investigated. Analytical solutions for the elastic displacements and the electric potentials under a uniform external strain are derived exactly. Taking into account of the coupling effects of elasticity, permittivity and piezoelectricity, the formula is derived for estimating the effective elastic properties based on the average field theory in the dilute limit. An elastic response mechanism is revealed, in which the effective elastic properties increase as inclusion piezoelectric properties increase and inclusion dielectric properties decrease. Moreover, a piezoelectric response mechanism, of which the effective piezoelectric response vanishes due to the symmetry of spherically anisotropic composite, is also disclosed. 相似文献
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We investigate in this article the thermal conductivity of array of cylinders embedded in a homogeneous matrix. Using Green's function, we confirm that the method invented by Rayleigh can be generalized to deal with thermal property of these systems. A technique for calculating effective thermal conductivities of these systems is proposed. As an example, we consider a system with square symmetry, and a neat formula for effective thermal conductivity is derived. We show that the method also includes the proof of Keller theorem. 相似文献
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1IntroductionTherheologyofcolloidaldispersionisofinterestinmanyphsicalandtechnologicalproblems,andforthisreasonithasbeenstudiedextensively,expeciallywhenthesystemcallI)edescribedbythelillearNavier-StokesequationsforincompressibleNewtonianfiuicl[1--6J.ColIoidaldispersioncanbesubdividedintotwoclasses,namely,suspensionandemulsi.I,[7'8].Asuspensionisadispersionwithfinerigidparticlessuspendedinafluid.Inanemulsion,pallidparticlesareimmersedinanotherfluid.Animportantprobleminthisfieldistodeters-f… 相似文献
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I.IntroductionWiththedevelopmentofsocietyandeconomyinmetropolises,thecontradictionbet\"eentheincreaseoftrat'ficflowandtheexistingconditionoftrafticftlcilitiesbecolllesmorealldmore'serious,resultinginaprincipalI'actorofconstrainingthedevelopmentofmetropolititneconomy.Therefore,inrecentdecadesthetrat'l'ictlowproblemhasdrawntheattelltiollofInanyspecialistsinvariousfieldsincludingphysics,mechanicsalldmathelllatics.Alargenumberoftraftic1llodelshavebeenpropes.Inthispaper,thecellularautomaton(CA)tr… 相似文献
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IntroductionTherheologyofcolloidaldispersionisofinterestinmanyphysicalandtechnologicalproblems,andforthisreasonithasbeenstudiedextensively,especiallywhenthesystemcanbedescribedbythelinearNavier_Stokesequations[1~3].Colloidaldispersioncanbesubdividedinto… 相似文献