We build the perturbation expansion method for nonlinear composite media and extend the EMA for nonlinear effective conductivity. Using the solutions of boundary-value problems of a cylindrical in- clusion, we derive ...We build the perturbation expansion method for nonlinear composite media and extend the EMA for nonlinear effective conductivity. Using the solutions of boundary-value problems of a cylindrical in- clusion, we derive formulae for nonlinear effective conductivity.展开更多
The effective dielectric response of linear composites containing graded material is investigated under an applied electric field E_0.For the cylindrical inclusion with gradient dielectric function,ει(r)=b+cr,random...The effective dielectric response of linear composites containing graded material is investigated under an applied electric field E_0.For the cylindrical inclusion with gradient dielectric function,ει(r)=b+cr,randomly embedded in a host with dielectric constant εm,we have obtained the exact solution of local electric potential of the composite media regions,which obeys a linear constitutive relation D=εE,using hypergeometric function.In dilute limit,we have derived the effective dielectric response of the linear composite media.Furthermore,for larger volume fraction,the formulas of effective dielectric response of the graded composite media are given.展开更多
The effective medium approximation (EMA) theory is the basis of a capacitance sensor used for concen-tration measurementof a particulate solid flow, its measurementresultis independenton particle size. In existence of...The effective medium approximation (EMA) theory is the basis of a capacitance sensor used for concen-tration measurementof a particulate solid flow, its measurementresultis independenton particle size. In existence ofparticle agglomeration or aggradation, however, it is found that the effective permittivity of a gas/solid mixture is de-pendent on particle size. In this paper, a parallel plate, differential capacitance sensor is utilized to investigate theinfluence of particle size on the effective permittivity of the mixture in such a case. Static experiments using threematerials including glass, limestone and quartz particles were carried out in an off-line manner. The volume fractionof particles being tested ranged from20×10-6to 600×10-6, while the particle size was between 3 and 100μm.Experimental results showthat the effective permittivity of a particle-gas mixture with particle agglomeration is largerthan that predicted by EMA and the smaller the particle size, the larger the effective permittivity. The experimentprocess and analysis results are discussed in detail in the paper.展开更多
Based on the effective medium approximation theory of composites, the empirical model proposed by Pandey and Kakar is remedied to investigate the microwave emissivity of sea surface under wave breaking driven by stron...Based on the effective medium approximation theory of composites, the empirical model proposed by Pandey and Kakar is remedied to investigate the microwave emissivity of sea surface under wave breaking driven by strong wind. In the improved model, the effects of seawater bubbles, droplets and difference in temperature of air and sea interface (DTAS) on the emissivity of sea surface covered by whitecaps are discussed. The model results indicate that the effective emissivity of sea surface in-creases with DTAS increasing, and the impacts of bubble structures and thickness of whitecaps layer on the emissivity are included in the model by introducing the effective dielectric constant of whitecaps layer. Moreover, a good agreement is obtained by comparing the model results with the Rose’s ex-perimental data.展开更多
通过参考有关文献关于卢瑟福背向散射能谱(rutherford back scattering spectrometry,RBS)、透射电镜(trans-mission electron microscope,TEM)、俄歇电子能谱(auger electron spectroscopy,AES)、红外反射谱法(infrared reflec-tion,IR...通过参考有关文献关于卢瑟福背向散射能谱(rutherford back scattering spectrometry,RBS)、透射电镜(trans-mission electron microscope,TEM)、俄歇电子能谱(auger electron spectroscopy,AES)、红外反射谱法(infrared reflec-tion,IR)等手段对绝缘衬底上硅(silicon-on-insulator,SOI)微结构的分析研究,提出并建立了一种基于SOI有效介质近似理论的多层薄膜结构模型。基于该模型,利用总反射系数对红外光谱进行模拟能很好地揭示此材料的光学表征,验证了红外反射光谱法作为一种高灵敏度的分析技术,无论是受SOI材料中所注硅岛的体积分数比,或是其几何分布等的影响,都能准确地反馈材料的光学表征信息。展开更多
文摘We build the perturbation expansion method for nonlinear composite media and extend the EMA for nonlinear effective conductivity. Using the solutions of boundary-value problems of a cylindrical in- clusion, we derive formulae for nonlinear effective conductivity.
文摘The effective dielectric response of linear composites containing graded material is investigated under an applied electric field E_0.For the cylindrical inclusion with gradient dielectric function,ει(r)=b+cr,randomly embedded in a host with dielectric constant εm,we have obtained the exact solution of local electric potential of the composite media regions,which obeys a linear constitutive relation D=εE,using hypergeometric function.In dilute limit,we have derived the effective dielectric response of the linear composite media.Furthermore,for larger volume fraction,the formulas of effective dielectric response of the graded composite media are given.
文摘The effective medium approximation (EMA) theory is the basis of a capacitance sensor used for concen-tration measurementof a particulate solid flow, its measurementresultis independenton particle size. In existence ofparticle agglomeration or aggradation, however, it is found that the effective permittivity of a gas/solid mixture is de-pendent on particle size. In this paper, a parallel plate, differential capacitance sensor is utilized to investigate theinfluence of particle size on the effective permittivity of the mixture in such a case. Static experiments using threematerials including glass, limestone and quartz particles were carried out in an off-line manner. The volume fractionof particles being tested ranged from20×10-6to 600×10-6, while the particle size was between 3 and 100μm.Experimental results showthat the effective permittivity of a particle-gas mixture with particle agglomeration is largerthan that predicted by EMA and the smaller the particle size, the larger the effective permittivity. The experimentprocess and analysis results are discussed in detail in the paper.
基金the National Natural Science Foundation of China (Grant No.40476062)the National "863" Project of China (Grant Nos.2002AA639270 and 2002AA633130)
文摘Based on the effective medium approximation theory of composites, the empirical model proposed by Pandey and Kakar is remedied to investigate the microwave emissivity of sea surface under wave breaking driven by strong wind. In the improved model, the effects of seawater bubbles, droplets and difference in temperature of air and sea interface (DTAS) on the emissivity of sea surface covered by whitecaps are discussed. The model results indicate that the effective emissivity of sea surface in-creases with DTAS increasing, and the impacts of bubble structures and thickness of whitecaps layer on the emissivity are included in the model by introducing the effective dielectric constant of whitecaps layer. Moreover, a good agreement is obtained by comparing the model results with the Rose’s ex-perimental data.
文摘通过参考有关文献关于卢瑟福背向散射能谱(rutherford back scattering spectrometry,RBS)、透射电镜(trans-mission electron microscope,TEM)、俄歇电子能谱(auger electron spectroscopy,AES)、红外反射谱法(infrared reflec-tion,IR)等手段对绝缘衬底上硅(silicon-on-insulator,SOI)微结构的分析研究,提出并建立了一种基于SOI有效介质近似理论的多层薄膜结构模型。基于该模型,利用总反射系数对红外光谱进行模拟能很好地揭示此材料的光学表征,验证了红外反射光谱法作为一种高灵敏度的分析技术,无论是受SOI材料中所注硅岛的体积分数比,或是其几何分布等的影响,都能准确地反馈材料的光学表征信息。
