采用电流密度拉普拉斯变换(Current Density Laplace Transform)方法将无子时间步的蛙跳式交替方向隐式时域有限差分(leapfrog-ADI-FDTD)方法应用于等离子体的电磁计算中,得到了等离子体中的迭代公式。为了验证该方法的有效性,计算了等...采用电流密度拉普拉斯变换(Current Density Laplace Transform)方法将无子时间步的蛙跳式交替方向隐式时域有限差分(leapfrog-ADI-FDTD)方法应用于等离子体的电磁计算中,得到了等离子体中的迭代公式。为了验证该方法的有效性,计算了等离子体平板的反射系数和透射系数,并与几种传统的FDTD方法进行了对比,数值实验表明,提出的算法具有无条件稳定性,精度和效率高于普通的显式FDTD方法。展开更多
With the linear interpolation method, an improved absorbing boundary condition(ABC)is introduced and derived, which is suitable for the alternating-direction-implicit finite- difference time-domain (ADI-FDTD) meth...With the linear interpolation method, an improved absorbing boundary condition(ABC)is introduced and derived, which is suitable for the alternating-direction-implicit finite- difference time-domain (ADI-FDTD) method. The reflection of the ABC caused by both the truncated error and the phase velocity error is analyzed. Based on the phase velocity estimation and the nonuniform cell, two methods are studied and then adopted to improve the performance of the ABC. A calculation case of a rectangular waveguide which is a typical dispersive transmission line is carried out using the ADI-FDTD method with the improved ABC for evaluation. According to the calculated case, the comparison is given between the reflection coefficients of the ABC with and without the velocity estimation and also the comparison between the reflection coefficients of the ABC with and without the nonuniform processing. The reflection variation of the ABC under different time steps is also analyzed and the acceptable worsening will not obscure the improvement on the absorption. Numerical results obviously show that efficient improvement on the absorbing performance of the ABC is achieved based on these methods for the ADI-FDTD.展开更多
The paper has introduced characteristics and study status of new rural construction, illustrated the connotation of leapfrog development of new rural construction, and considered that new rural construction is an impo...The paper has introduced characteristics and study status of new rural construction, illustrated the connotation of leapfrog development of new rural construction, and considered that new rural construction is an important measure to solve "three rural" problems. How to conduct new rural construction in urbanization is a critical issue in social and economic development in China. Based on the favorable condition and development mode of current new rural construction, by taking new rural construction of Haiyang Village in Jiangxia District of Wuhan City for example, it has analyzed the leapfrog development in terms of traditional agriculture, villagers' life quality and rural concept, and the inheritance in terms of culture and rural appearance, so as to give enlightenments to new rural construction in the future.展开更多
Several new energy identities of the two dimenslonal(2D) Maxwell equations in a lossy medium in the case of the perfectly electric conducting boundary conditions are proposed and proved. These identities show a new ...Several new energy identities of the two dimenslonal(2D) Maxwell equations in a lossy medium in the case of the perfectly electric conducting boundary conditions are proposed and proved. These identities show a new kind of energy conservation in the Maxwell system and provide a new energy method to analyze the alternating direction im- plicit finite difference time domain method for the 2D Maxwell equations (2D-ADI-FDTD). It is proved that 2D-ADI-FDTD is approximately energy conserved, unconditionally sta- ble and second order convergent in the discrete L2 and H1 norms, which implies that 2D-ADI-FDTD is super convergent. By this super convergence, it is simply proved that the error of the divergence of the solution of 2D-ADI-FDTD is second order accurate. It is also proved that the difference scheme of 2D-ADI-FDTD with respect to time t is second order convergent in the discrete H1 norm. Experimental results to confirm the theoretical analysis on stability, convergence and energy conservation are presented.展开更多
文摘采用电流密度拉普拉斯变换(Current Density Laplace Transform)方法将无子时间步的蛙跳式交替方向隐式时域有限差分(leapfrog-ADI-FDTD)方法应用于等离子体的电磁计算中,得到了等离子体中的迭代公式。为了验证该方法的有效性,计算了等离子体平板的反射系数和透射系数,并与几种传统的FDTD方法进行了对比,数值实验表明,提出的算法具有无条件稳定性,精度和效率高于普通的显式FDTD方法。
基金The National Natural Science Foundation of China(No.60702027)the Free Research Fund of the National Mobile Communications Research Laboratory of Southeast University (No.2008B07)the National Basic Research Program of China(973 Program)(No.2007CB310603)
文摘With the linear interpolation method, an improved absorbing boundary condition(ABC)is introduced and derived, which is suitable for the alternating-direction-implicit finite- difference time-domain (ADI-FDTD) method. The reflection of the ABC caused by both the truncated error and the phase velocity error is analyzed. Based on the phase velocity estimation and the nonuniform cell, two methods are studied and then adopted to improve the performance of the ABC. A calculation case of a rectangular waveguide which is a typical dispersive transmission line is carried out using the ADI-FDTD method with the improved ABC for evaluation. According to the calculated case, the comparison is given between the reflection coefficients of the ABC with and without the velocity estimation and also the comparison between the reflection coefficients of the ABC with and without the nonuniform processing. The reflection variation of the ABC under different time steps is also analyzed and the acceptable worsening will not obscure the improvement on the absorption. Numerical results obviously show that efficient improvement on the absorbing performance of the ABC is achieved based on these methods for the ADI-FDTD.
文摘The paper has introduced characteristics and study status of new rural construction, illustrated the connotation of leapfrog development of new rural construction, and considered that new rural construction is an important measure to solve "three rural" problems. How to conduct new rural construction in urbanization is a critical issue in social and economic development in China. Based on the favorable condition and development mode of current new rural construction, by taking new rural construction of Haiyang Village in Jiangxia District of Wuhan City for example, it has analyzed the leapfrog development in terms of traditional agriculture, villagers' life quality and rural concept, and the inheritance in terms of culture and rural appearance, so as to give enlightenments to new rural construction in the future.
基金supported by Shandong Provincial Natural Science Foundation(Y2008A19)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘Several new energy identities of the two dimenslonal(2D) Maxwell equations in a lossy medium in the case of the perfectly electric conducting boundary conditions are proposed and proved. These identities show a new kind of energy conservation in the Maxwell system and provide a new energy method to analyze the alternating direction im- plicit finite difference time domain method for the 2D Maxwell equations (2D-ADI-FDTD). It is proved that 2D-ADI-FDTD is approximately energy conserved, unconditionally sta- ble and second order convergent in the discrete L2 and H1 norms, which implies that 2D-ADI-FDTD is super convergent. By this super convergence, it is simply proved that the error of the divergence of the solution of 2D-ADI-FDTD is second order accurate. It is also proved that the difference scheme of 2D-ADI-FDTD with respect to time t is second order convergent in the discrete H1 norm. Experimental results to confirm the theoretical analysis on stability, convergence and energy conservation are presented.