Mode matching method is used to analyze the scattering characteristics of thecircular-to-circular groove waveguide junction. Matching the electric fields and magnetic fields atthe boundary of the junction, and multipl...Mode matching method is used to analyze the scattering characteristics of thecircular-to-circular groove waveguide junction. Matching the electric fields and magnetic fields atthe boundary of the junction, and multiplying the mode functions of the circular waveguide andcircular groove waveguide on both sides of the boundary equation, the scattering matrix equation isobtained, the scattering coefficients can be obtained from the equation. Then the scatteringcharacteristics of the iris with circular window in circular groove waveguide are analyzed. At lastthe convergent problem is discussed; when choosing a suitable mode group, convergent numericalresults are obtained, and the frequency response of the iris' scattering coefficients is also given.展开更多
The thermal boundary conductance of Al/SiO2, Al/Si, Au/SiO2, and Au/Si are measured by a femtosecond laser transient thermoreflectance technique. The distinct differences of the interfacial thermal conductance between...The thermal boundary conductance of Al/SiO2, Al/Si, Au/SiO2, and Au/Si are measured by a femtosecond laser transient thermoreflectance technique. The distinct differences of the interfacial thermal conductance between these samples are observed. For the same metal film, the thermal boundary conductance between metal and substrate decreases with the thermal conductivity of the substrate. The measured results are explained with the phonon diffusion mismatch model by introducing a phonon transmission coefficient across the interface.展开更多
We consider the problem of the two-point resistance on an m ×n cobweb network with a 2r boundary, which has never been solved before. Up to now researchers just only solved the cases with free boundary or null re...We consider the problem of the two-point resistance on an m ×n cobweb network with a 2r boundary, which has never been solved before. Up to now researchers just only solved the cases with free boundary or null resistor boundary. This paper gives the general formulae of the resistance between any two nodes in both tinite and infinite cases using a method of direct summation pioneered by Tan [Z. Z. Tan, et al., J. Phys. A 46 (2013) 195202], which is simpler and can be easier to use in practice. This method contrasts the Green's function technique and the Laplacian matrix approach, which is difllcult to apply to the geometry of a cobweb with a 2r boundary. We deduce several interesting results according to our genera/formula. In the end we compare and illuminate our formulae with two examples. Our analysis gives the result directly as a single summation, and the result is mainly composed of the characteristic roots.展开更多
The effective thermal conductivity of composites with ellipsoidal fillers is analyzed by using a homogenization method that is able to represent the microstructure precisely.In this study,various parameters such as th...The effective thermal conductivity of composites with ellipsoidal fillers is analyzed by using a homogenization method that is able to represent the microstructure precisely.In this study,various parameters such as the volume fraction,shape,and distribution of the filler are quantitatively estimated to understand the mechanisms of heat transfer in the composite.First,thermal boundary resistance between resin and filler is important for obtaining composites with higher thermal conductivity.Second,the anisotropy of the effective thermal conductivity arises from contact between filler in the case of ellipsoidal filler and produces lower thermal resistance.Finally,the filler network and thermal resistance are essential for the heat transfer in composites because the path of thermal conduction is improved by contact between neighboring filler particles.展开更多
文摘Mode matching method is used to analyze the scattering characteristics of thecircular-to-circular groove waveguide junction. Matching the electric fields and magnetic fields atthe boundary of the junction, and multiplying the mode functions of the circular waveguide andcircular groove waveguide on both sides of the boundary equation, the scattering matrix equation isobtained, the scattering coefficients can be obtained from the equation. Then the scatteringcharacteristics of the iris with circular window in circular groove waveguide are analyzed. At lastthe convergent problem is discussed; when choosing a suitable mode group, convergent numericalresults are obtained, and the frequency response of the iris' scattering coefficients is also given.
基金supported by the National Basic Research Program of China ("973" Project) (Grant No. 2011CB707605)the National Nature Science Foundation of China (Grant Nos. 50875047, 50776017, 50925519, 51106029)
文摘The thermal boundary conductance of Al/SiO2, Al/Si, Au/SiO2, and Au/Si are measured by a femtosecond laser transient thermoreflectance technique. The distinct differences of the interfacial thermal conductance between these samples are observed. For the same metal film, the thermal boundary conductance between metal and substrate decreases with the thermal conductivity of the substrate. The measured results are explained with the phonon diffusion mismatch model by introducing a phonon transmission coefficient across the interface.
文摘We consider the problem of the two-point resistance on an m ×n cobweb network with a 2r boundary, which has never been solved before. Up to now researchers just only solved the cases with free boundary or null resistor boundary. This paper gives the general formulae of the resistance between any two nodes in both tinite and infinite cases using a method of direct summation pioneered by Tan [Z. Z. Tan, et al., J. Phys. A 46 (2013) 195202], which is simpler and can be easier to use in practice. This method contrasts the Green's function technique and the Laplacian matrix approach, which is difllcult to apply to the geometry of a cobweb with a 2r boundary. We deduce several interesting results according to our genera/formula. In the end we compare and illuminate our formulae with two examples. Our analysis gives the result directly as a single summation, and the result is mainly composed of the characteristic roots.
文摘The effective thermal conductivity of composites with ellipsoidal fillers is analyzed by using a homogenization method that is able to represent the microstructure precisely.In this study,various parameters such as the volume fraction,shape,and distribution of the filler are quantitatively estimated to understand the mechanisms of heat transfer in the composite.First,thermal boundary resistance between resin and filler is important for obtaining composites with higher thermal conductivity.Second,the anisotropy of the effective thermal conductivity arises from contact between filler in the case of ellipsoidal filler and produces lower thermal resistance.Finally,the filler network and thermal resistance are essential for the heat transfer in composites because the path of thermal conduction is improved by contact between neighboring filler particles.