提出了一种分析多层印刷电路板电源分配网络(power distribution network,PDN)中一维(1D)介质型电磁带隙(electromagnetic band-gap,EBG)结构噪声隔离性能的1D有限元数值计算方法.将1D介质型EBG的3D结构简化为1D有限元模型,通过直接求...提出了一种分析多层印刷电路板电源分配网络(power distribution network,PDN)中一维(1D)介质型电磁带隙(electromagnetic band-gap,EBG)结构噪声隔离性能的1D有限元数值计算方法.将1D介质型EBG的3D结构简化为1D有限元模型,通过直接求解波动方程获得传输系数T、反射系数R以及散射参数S.利用R-T曲线可直观地判定频率禁带,而采用分贝表示的S21参数则更方便评价噪声隔离度.根据介质型EBG的周期数、介电常数和周期长度等参数对噪声隔离性能影响的仿真结果,针对少周期、不完全禁带EBG结构提出了先采用多周期EBG结构预测禁带,再通过调整介电常数和周期长度扩展禁带和增强噪声隔离度的两阶段设计方法.采用3D全波电磁仿真验证了1D有限元算法的合理性.展开更多
The effect of electron itineracy on the magnetism of S＝1/2 ferromagnetic Ising model is investigated by introducing a hopping term. The electron Green's function method is used to deal with this Hamiltonian. Here...The effect of electron itineracy on the magnetism of S＝1/2 ferromagnetic Ising model is investigated by introducing a hopping term. The electron Green's function method is used to deal with this Hamiltonian. Here emphasis is made on that the magnetization is caused by the difference between the filling of spin-up and spin-down electrons.This concept is in accordance with that of band structure theory. In the zero band width limit, our results are the same as obtained by spin Green's function method. However, our method achieves more detailed physical information. The spontaneous magnetization, Curie temperature, total energy, and specific heat are calculated and investigated in detail by the densities of states. Hopping term depresses the Curie temperature but remains the order-disorder transformation still to be second order transition. Above the transition point, the energy band is the same as that of tight binding system because exchange interaction has no effect anymore. While under the transition point, the energy band splits into two subbands due to exchange interaction.展开更多
The wideband electromagnetic characteristics of missile targets in midcourse are the foundation of midcourse attack-defense confrontation. This paper proposes a novel electromagnetic scattering modeling method for mid...The wideband electromagnetic characteristics of missile targets in midcourse are the foundation of midcourse attack-defense confrontation. This paper proposes a novel electromagnetic scattering modeling method for midcourse targets based on a pre- cise scattering center model, in which the nonideal scattering phenomenon, shielding effect and micro-motion are taken into consideration for the first time. Firstly, a precise scattering center model incorporating both the sliding scattering and artist- tropic scattering is established. Then the change rule of the target attitude is generalized, and a checking method of the scatter- ing center shielding effect is proposed for rotationally symmetric targets. Afterwards, a novel dynamic electromagnetic scat- tering model is presented, where the scattering center model updates along with the variation of the target attitude and can characterize the change of the electromagnetic characteristics of midcourse targets exactly. Finally, in light of the established model, the dynamic electromagnetic characteristics within different attitude angle bounds are analyzed by stages, and some useful conclusions are obtained. Experiment results from the measured data in anechoic chamber verify the validity of the proposed modeling method and relevant analysis.展开更多
The effects of the nuclear current in the antimagnetic rotation band of 105Cd have been investigated in a fully self-consistent and microscopic way by using the tilted axis cranking relativistic mean-field model.It wa...The effects of the nuclear current in the antimagnetic rotation band of 105Cd have been investigated in a fully self-consistent and microscopic way by using the tilted axis cranking relativistic mean-field model.It was found that the inclusion of nuclear current leads to a higher angular momentum and thus a larger kinetic moment of inertia at a given rotational frequency.As a consequence,the B(E2) values with current are always smaller than those without current.展开更多
文摘提出了一种分析多层印刷电路板电源分配网络(power distribution network,PDN)中一维(1D)介质型电磁带隙(electromagnetic band-gap,EBG)结构噪声隔离性能的1D有限元数值计算方法.将1D介质型EBG的3D结构简化为1D有限元模型,通过直接求解波动方程获得传输系数T、反射系数R以及散射参数S.利用R-T曲线可直观地判定频率禁带,而采用分贝表示的S21参数则更方便评价噪声隔离度.根据介质型EBG的周期数、介电常数和周期长度等参数对噪声隔离性能影响的仿真结果,针对少周期、不完全禁带EBG结构提出了先采用多周期EBG结构预测禁带,再通过调整介电常数和周期长度扩展禁带和增强噪声隔离度的两阶段设计方法.采用3D全波电磁仿真验证了1D有限元算法的合理性.
文摘The effect of electron itineracy on the magnetism of S＝1/2 ferromagnetic Ising model is investigated by introducing a hopping term. The electron Green's function method is used to deal with this Hamiltonian. Here emphasis is made on that the magnetization is caused by the difference between the filling of spin-up and spin-down electrons.This concept is in accordance with that of band structure theory. In the zero band width limit, our results are the same as obtained by spin Green's function method. However, our method achieves more detailed physical information. The spontaneous magnetization, Curie temperature, total energy, and specific heat are calculated and investigated in detail by the densities of states. Hopping term depresses the Curie temperature but remains the order-disorder transformation still to be second order transition. Above the transition point, the energy band is the same as that of tight binding system because exchange interaction has no effect anymore. While under the transition point, the energy band splits into two subbands due to exchange interaction.
基金supported by the National Science Fund for Distinguished Young Scholars of China (Grant No. 61025006)
文摘The wideband electromagnetic characteristics of missile targets in midcourse are the foundation of midcourse attack-defense confrontation. This paper proposes a novel electromagnetic scattering modeling method for midcourse targets based on a pre- cise scattering center model, in which the nonideal scattering phenomenon, shielding effect and micro-motion are taken into consideration for the first time. Firstly, a precise scattering center model incorporating both the sliding scattering and artist- tropic scattering is established. Then the change rule of the target attitude is generalized, and a checking method of the scatter- ing center shielding effect is proposed for rotationally symmetric targets. Afterwards, a novel dynamic electromagnetic scat- tering model is presented, where the scattering center model updates along with the variation of the target attitude and can characterize the change of the electromagnetic characteristics of midcourse targets exactly. Finally, in light of the established model, the dynamic electromagnetic characteristics within different attitude angle bounds are analyzed by stages, and some useful conclusions are obtained. Experiment results from the measured data in anechoic chamber verify the validity of the proposed modeling method and relevant analysis.
基金supported by the National Basic Research Program of China(Grant No.2007CB815000)the National Natural Science Foundation of China(Grant Nos.10975008, 11105005 and 11175002)the Research Fund for the Doctoral Program of Higher Education(Grant No.20110001110087)
文摘The effects of the nuclear current in the antimagnetic rotation band of 105Cd have been investigated in a fully self-consistent and microscopic way by using the tilted axis cranking relativistic mean-field model.It was found that the inclusion of nuclear current leads to a higher angular momentum and thus a larger kinetic moment of inertia at a given rotational frequency.As a consequence,the B(E2) values with current are always smaller than those without current.
