传输矩阵法分析各向异性介质微带线色散特性

从电磁场切向分量的通解形式出发,提出一种求解电磁场传输矩阵的新算法.分析了微带线色散特性与各向异性介质参数之间的关系,得出以下结果,在频率为20 GHz时,介电常数张量ε和磁导率张量μ中的矩阵元对微带线色散特性的影响从大到小的顺序为ε2,μ1,ε1,μ2,μ3和ε3.进一步分析表明,选择合适的介质参数,不同介质衬底的微...     

带有频谱补偿的基频修改算法

针对当前多数在基于拼接的语音合成系统中使用的基频修改算法缺少对频谱进行补偿的情况,提出了一种带有频谱补偿的基频修改算法.在传统基音同步叠加(PSOLA)算法的基础上,以共振峰参数和频谱倾斜参数描述频谱特性,通过对频谱参数进行预测及修改,在修改基频的同时,有效地补偿了频谱特性.频谱参数的预测公式由各基频下的条件概率密度函数导出,频谱参数的修改通过正弦模型实现.实验表明,对于不同的汉语元音、基频修改因子和听者,在平均86.25%的情况下,该算法较传统PSOLA算法能够获得更接近自然音质的语音.     

手征负折射媒质对称平板波导的色散特性

根据麦克斯韦方程组以及手征媒质的本构关系, 研究了手征负折射平板波导的色散特性. 通过引入归一化频率、归一化传播常数, 得到了用归一化参数表示的手征负折射平板波导的色散方程. 数值计算结果表明, 手征参数对平板波导的色散特性影响很大. 当相对手征参数约为0.047 7 时, 左旋极化波零阶模消失; 当相对手征参数大于1, 即为手征负折射媒质时, 存在零阶模. 此外, 还比较了手征负折射媒质平板波导和一般手征媒质平板波导的色散曲线变化趋势.     

高温超导微带线的传输特性及其应用

研究了高温超导微带线的衰减和色散特性。推导了超导体的复电导率和外加直流电流的关系。考虑到实际高温超导材料中分布着约瑟夫逊结并且存在一定的剩余电导率，对复电导率公式作了修正。当微带线的带条厚度和穿透深度相当时，用唯象损耗等效方法分析了电磁场渗人超导体而对微波传输特性产生的影响。     

Hankel transform domain analysis of dual-frequency stacked circular microstrip antennas

This paper presents an accurate and efficient method for the computation of resonant frequencies and radiation patterns of a dual-frequency stacked circular microstrip antenna. The problem is first formulated using the Hankel transform domain approach and expressions are obtained for the Green's function in the Hankel transform domain, which relates the electric surface currents on the circular disks and tangential electric field components on the surfaces of the substrates. Then Galerkin's method together with Parsebal's relation for Hankel transformation is used to solve for the unknown currents. In the derivation process, the resonant frequencies are numerically determined as a function of the radii of two circular disks and thicknesses and relative permittivies of two substrates. Finally, the far-zone radiation patterns are directly obtained from the Green's function and the currents. The numerical results for the resonant frequencies and radiation patterns are in excellent agreement with the available experimental data corroborating the accuracy of the present method. Huang Jingxi: born in Nov. 1937, Professor     

Temperature dependent spectral response characteristic of III-V compound tandem cell

The GaInP/GaAs/Ge triple-junction tandem cells with a conversion efficiency of 27.1% were fabricated using metalorganic chemical vapor deposition (MOCVD) technique. Temperature dependence of the spectral response measurements of the GaInP/GaAs/Ge tandem cell was performed by a quantum effi-ciency system at temperatures ranging from 25℃ to 160℃. The red-shift phenomena of the absorption limit for all subcells were observed with increasing temperature, which is dued to the energy gap nar-rowing with temperature. The short-circuit current densities (J_sc)of GaInP, GaAs and Ge subcells at room temperature calculated based on the spectral response data were 12.9, 13.7 and 17 mA/cm², re-spectively. The temperature coefficient of J_sc for the tandem cell was determined to be 8.9 mA/(cm²·℃), and the corresponding temperature coefficient of the open-circuit voltage deduced from the se-ries-connected model was -6.27 mV/℃.     

两种脉搏信号的声学检测与谱特征分析

用一种声学检测系统对人体两种脉象进行了检测与分析,获得了自谱(autospectrum)和倒谱(cepstrum)特征参数,结果表明,滑脉和细弦脉在倒谱上差异比自谱更为显著.     

波达方向估计的一种改进SVD算法

本文主研究智能天线算法中的关键技术波达方向估计（DOA）。针对相干信号源的信号子空间与噪声子空间相互渗透,导致空间协方差矩阵缺秩从而经典算法失效的问题,本文基于奇异值分解（SVD）算法,提出了一种改进的SVD算法。该算法利用入射信号矩阵的最大特征向量元素包含所有入射信号信息的性质,进行矩阵重构,并对重构矩阵进行特征值分解得到噪声子空间和信号子空间,最后利用经典谱估计算法得到相干信源的入射方向。仿真试验结果表明改进SVD算法性能优于原始算法。     

TiF分子P线系跃迁谱线的研究

应用最近建立的能正确预言双原子分子P线系高激发振转跃迁谱线的新公式,首次研究了TiF分子在次带G⁴Φ_5/2-X⁴Φ_5/2跃迁体系内（0,1）跃迁带的P支发射光谱.研究结果表明,该方法不仅可以精确地重复已知的实验谱线数据,而且从理论上预测了现阶段实验上难以获得的包含转动量子数J=90.5在内的高激发振转态发射谱线的正确数据.