Scaling of vortex transport properties and nonlinear ac response of high-temperature superconductors

The macroscopic behavior of high-temperature superconductors is described by a nonlinear response function in combinations with Maxwell equations. This function is compatible with the suggested different model pinning barriers U(J). A comparison of this function to the scaling behavior of the isothermal current-voltage characteristics measured in twinned YBa₂Cu₃O (YBCO) samples shows fair agreement. We also compare the amplitude dependence of ac susceptibility derived from this function with several experimental results of high-temperature superconductors and find a general power law in the out-of-phase peak shift. Received 4 August 1999 and Received in final form 30 November 1999     

On Anomalous Propagation in Transversely Uniaxial Bianisotropic Mediums

We consider the propagation of a plane electromagnetic wave in transversely uniaxial bianisotropic mediums (TUBMS). Anomalous propagation takes place when a certain condition is fulfilled by the constitutive parameters of the medium. A detailed field analysis for this anomalous behaviour is provided.     

平板目标与随机粗糙面对电磁波的复合散射

建立了平板目标与随机粗糙面的复合散射模型,求解过程包括用板上感应电流的谱域积分表示平板目标的初级散射场;用物理光学方法计算随机粗糙面的次级散射场和统计分析复合散射的平均散射功率．通过选用正态分布粗糙面作为计算实例．数值结果显示出平板目标与随机粗糙面之间相互作用散射分量的重要性及空间分布特性．     

推力电磁轴承的电磁场分析

利用有限元法对推力电磁轴承的磁场分布进行了分析计算,并通过对某一实际电磁轴承的推力轴承磁场分布及漏磁的分析计算,得出了推力轴承和推力盘之间的气隙及推力轴承和转子之间的气隙之比的最佳设计值,所得结果可作为推力电磁轴承实际设计的准则     

Numerical modeling of frequency influence on the electromagnetic stirring of semiconductor melts

Alternating magnetic fields can be used in order to increase the level of convection and to mix the doped semiconductor alloys. A numerical analysis of the electromagnetic induced convection in GaInSb semiconductor melts is performed by using the software package CrysVUn. The magnetic field parameters are varied in order to obtain a maximum efficiency of the induced convection with a minimum quantity of the heat released in the melt. The influence of the electrical current frequency on the convection intensity is analyzed for samples with various radii (R = 0.5 – 3cm). Numerical procedure is validated by comparing the numerical results obtained in mercury samples with the experimental data given from the literature, which show a maximum stirring for a magnetic skin depth δ = 0.2R , in the case of a mercury sample with the radius R = 10 cm. This maximum corresponds to a shielding parameter R _ω = 40. Our numerical results show that the value of the shielding parameter for which the convection intensity reaches the maximum depends on the sample radius and increases when the sample radius increases. The results of this analysis are important in the case of samples with small radius, when a good mixing of the melt can be obtained for frequencies much lower than those corresponding to a shielding parameter R_ω = 40. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Propagation of electromagnetic wave in the three phases soil media

IntroductionItisofparamountimportancetogetgeotechnicalparameterssuchasmoisture ,compactness,andshearstrengthforgeotechnicalengineeringtransaction .Butthemethodtofetchthesoilsamplesforlaboratorytestcannotavoidbringingthedisturbance ,andmakethetestresultsinconsistenttotheactualstatusofsoil.Inrecentyears,theapplicationofEMwaveinthedetectinghiddentroublesindamsandundergroundfoundationsdevelopedrapidly .Buttherearestillsomefactorsthatrestricttheadvanceofapplication .Firstly ,thesoilconstitutesthr…     

Wave shaping through finite electromagnetic bandgap structure

Transmission mechanisms and wave steering under localized feeding conditions through a finite electromagnetic bandgap structure are investigated both experimentally and theoretically. The artificial propagating medium consists of a two-dimensional metallic wire structure dimensioned for millimetre wave operation. By analogy with electron propagation in semiconductor heterostructures, the signatures of ‘modal‘ and ‘fluid‘ propagation regimes are experimentally demonstrated. Data are then analysed through electric field patterns calculated by means of a three-dimensional solver of Maxwell‘s equations.     

菲涅耳公式的几何图示与应用

电磁波通过两种透明介质的分界面时,反射波、折射波和入射波的电矢量分量的大小和方向之间的关系可由菲涅耳公式说明,作通过分析和推导,给出了菲涅耳公式的几何图示,这使得在分析光学问题时,谱得简单和直观。