针对包含精细结构的电大尺寸目标电磁散射快速计算问题,提出了一种计算包含精细结构的电大尺寸目标电磁散射问题的基于矩阵降维的混合算法。该方法在Rao-Wilton-Glisson基函数矩量法(method of moment,MoM)的基础上,对目标区域进行划分...针对包含精细结构的电大尺寸目标电磁散射快速计算问题,提出了一种计算包含精细结构的电大尺寸目标电磁散射问题的基于矩阵降维的混合算法。该方法在Rao-Wilton-Glisson基函数矩量法(method of moment,MoM)的基础上,对目标区域进行划分,完成阻抗矩阵的分块和未知量的分离,再由矩量区与物理光学(physical optics,PO)区之间的电流相互作用构造耦合转移矩阵和激励转移矩阵,从而建立两个区域未知量之间的线性关系,进而完成对阻抗矩阵的降维,最终从矩阵运算角度构建了一种MoM-PO混合算法。其中,使用等效电偶极子模型简化双重积分计算,进一步减少矩阵元素的计算量;阻抗矩阵的阶数大幅减少,避免了大规模矩阵方程的求解计算。算例结果表明,与传统的低频算法相比,该算法既保证了计算精度,又提高了计算效率。展开更多
When calculating electromagnetic scattering using method of moments （MoM）, integral of the singular term has a significant influence on the results. This paper transforms the singular surface integral to the contour...When calculating electromagnetic scattering using method of moments （MoM）, integral of the singular term has a significant influence on the results. This paper transforms the singular surface integral to the contour integral. The integrand is expanded to Taylor series and the integral results in a closed form. The cut-off error is analyzed to show that the series converges fast and only about 2 terms can agree wel with the accurate result. The comparison of the perfect electric conductive （PEC） sphere＇s bi-static radar cross section （RCS） using MoM and the accurate method validates the feasibility in manipulating the singularity. The error due to the facet size and the cut-off terms of the series are analyzed in examples.展开更多
于2010年5月、7月、8月和10月对桑沟湾筏式养鲍区的沉积环境进行现场调查,采用挪威海洋研究所建立的鱼类养殖环境监测系统模型(Modelling-Ongrowing fish farms-Monitoring,MOM system),应用MOM-B着重对鲍养殖区的沉积环境状况进行监测...于2010年5月、7月、8月和10月对桑沟湾筏式养鲍区的沉积环境进行现场调查,采用挪威海洋研究所建立的鱼类养殖环境监测系统模型(Modelling-Ongrowing fish farms-Monitoring,MOM system),应用MOM-B着重对鲍养殖区的沉积环境状况进行监测和评价,由生物、化学和感官指标组组成。生物指标组的结果显示,各站位都有大型底栖动物,鲍养殖区处于1,2或者3等级。根据化学指标组(pH值和氧化还原电位Eh)和感官指标组(颜色、气味、气泡、粘稠度等)的监测结果进行了进一步的评价,结果显示,各站位的pH>7.0,为弱碱性,沉积物都无气泡产生,无臭味或硫化氢气味。鲍养殖区的沉积环境状况整体良好,5月和7月为1级,8月和10月为2级。虽然鲍养殖区目前的沉积环境状况较好,但需要注意的是8月和10月Eh<0,沉积环境已经处于还原状态,可能与鲍养殖压力有关。展开更多
为了解决如何构造具有通用逼近性能的Mamdani模糊系统问题,提出一类Mamdani模糊系统具有通用逼近性的充要条件.该模糊系统采用乘积推理机(product inference engine,PIE)和最大值平均(mean of maximum,MOM)解模糊器,按模糊规则后件分为...为了解决如何构造具有通用逼近性能的Mamdani模糊系统问题,提出一类Mamdani模糊系统具有通用逼近性的充要条件.该模糊系统采用乘积推理机(product inference engine,PIE)和最大值平均(mean of maximum,MOM)解模糊器,按模糊规则后件分为单点规则后件和模糊数规则后件两种情况,分别根据Weierstrass第一定理和隶属度函数性质给出了严格证明.最后通过示例证明该充要条件的有效性.展开更多
An efficient hybrid method based on the method of moments （MOM） and physical optics （PO） for the analysis of radiation characteristics of an electrically large antenna-radome system is presented. Specifically, MOM...An efficient hybrid method based on the method of moments （MOM） and physical optics （PO） for the analysis of radiation characteristics of an electrically large antenna-radome system is presented. Specifically, MOM is first applied to the antenna to find the current on its surface, and then the equivalent PO currents produced by the antenna radiation are assumed on the radome wall. When the coupling of the PO currents and antenna current is considered, the coupling matrix is divided into a series of partial matrices, in order to deduce the memory requirement and accelerate the evaluation process. Numerical results indicate that the proposed hybrid PO-MOM method is accurate and efficient.展开更多
文摘针对包含精细结构的电大尺寸目标电磁散射快速计算问题,提出了一种计算包含精细结构的电大尺寸目标电磁散射问题的基于矩阵降维的混合算法。该方法在Rao-Wilton-Glisson基函数矩量法(method of moment,MoM)的基础上,对目标区域进行划分,完成阻抗矩阵的分块和未知量的分离,再由矩量区与物理光学(physical optics,PO)区之间的电流相互作用构造耦合转移矩阵和激励转移矩阵,从而建立两个区域未知量之间的线性关系,进而完成对阻抗矩阵的降维,最终从矩阵运算角度构建了一种MoM-PO混合算法。其中,使用等效电偶极子模型简化双重积分计算,进一步减少矩阵元素的计算量;阻抗矩阵的阶数大幅减少,避免了大规模矩阵方程的求解计算。算例结果表明,与传统的低频算法相比,该算法既保证了计算精度,又提高了计算效率。
基金supported by the National Natural Science Foundationof China for the Youth(51307004)
文摘When calculating electromagnetic scattering using method of moments （MoM）, integral of the singular term has a significant influence on the results. This paper transforms the singular surface integral to the contour integral. The integrand is expanded to Taylor series and the integral results in a closed form. The cut-off error is analyzed to show that the series converges fast and only about 2 terms can agree wel with the accurate result. The comparison of the perfect electric conductive （PEC） sphere＇s bi-static radar cross section （RCS） using MoM and the accurate method validates the feasibility in manipulating the singularity. The error due to the facet size and the cut-off terms of the series are analyzed in examples.
文摘于2010年5月、7月、8月和10月对桑沟湾筏式养鲍区的沉积环境进行现场调查,采用挪威海洋研究所建立的鱼类养殖环境监测系统模型(Modelling-Ongrowing fish farms-Monitoring,MOM system),应用MOM-B着重对鲍养殖区的沉积环境状况进行监测和评价,由生物、化学和感官指标组组成。生物指标组的结果显示,各站位都有大型底栖动物,鲍养殖区处于1,2或者3等级。根据化学指标组(pH值和氧化还原电位Eh)和感官指标组(颜色、气味、气泡、粘稠度等)的监测结果进行了进一步的评价,结果显示,各站位的pH>7.0,为弱碱性,沉积物都无气泡产生,无臭味或硫化氢气味。鲍养殖区的沉积环境状况整体良好,5月和7月为1级,8月和10月为2级。虽然鲍养殖区目前的沉积环境状况较好,但需要注意的是8月和10月Eh<0,沉积环境已经处于还原状态,可能与鲍养殖压力有关。
文摘为了解决如何构造具有通用逼近性能的Mamdani模糊系统问题,提出一类Mamdani模糊系统具有通用逼近性的充要条件.该模糊系统采用乘积推理机(product inference engine,PIE)和最大值平均(mean of maximum,MOM)解模糊器,按模糊规则后件分为单点规则后件和模糊数规则后件两种情况,分别根据Weierstrass第一定理和隶属度函数性质给出了严格证明.最后通过示例证明该充要条件的有效性.
基金the National Natural Science Foundation of China (60471040)
文摘An efficient hybrid method based on the method of moments （MOM） and physical optics （PO） for the analysis of radiation characteristics of an electrically large antenna-radome system is presented. Specifically, MOM is first applied to the antenna to find the current on its surface, and then the equivalent PO currents produced by the antenna radiation are assumed on the radome wall. When the coupling of the PO currents and antenna current is considered, the coupling matrix is divided into a series of partial matrices, in order to deduce the memory requirement and accelerate the evaluation process. Numerical results indicate that the proposed hybrid PO-MOM method is accurate and efficient.
