查询词典 impedance

In the"willow leaf"TEM horn, the characteristic impedance varies from 50Ω to the 377Ω free space impedance, thus its metal plates have shapes similar to willow leaf. The constant impedance TEM horn consists of two tri-angular metal plates, with it's characteristic impedance at arbitrary cross-section being a constant.

采用FDTD方法，对'柳叶'TEM天线、恒阻抗TEM喇叭天线及低频补偿TEM喇叭天线的反射特性、口面场分布、主轴辐射场特性、辐射场方向特性进行了分析，并对各自的特性进行了比较。

From the lumped equivalent circuit model, the phase shift/attenuation and impedance characteristics of the novel structure are first analysed based on the Bloch theory, which shows the novel structure has properties analogous to those of a bandpass filter: the attenuation constant keeps zero with a continuous and smooth characteristic impedance distribution within the passband and the bandwidth may be arbitrarily specified; characteristic impedance is purely imaginary with the inhibition of the electromagetic wave propagation outside the passband.

首先从一般的等效电路模型出发，根据Bloch周期性理论对该结构的相移、衰减和阻抗特性进行了分析，结果表明该新结构具有类似带通滤波器的特性：通带内衰减常数为零，特性阻抗为实数并随频率连续平滑分布，具有可任意指定的阻抗匹配带宽；带外特性阻抗为纯虚数，电磁波传播受到抑制。

Intruduce impedance cardiography and describe its theoretical background, measuring methods, generation of impedance signals and its clinical meaning,and application of the impedance cardiography.

介绍心阻抗法的工作原理、测量方法、阻抗微分波的产生和临床意义，以及心阻抗法的临床用途。

A new conception of power per unit impedance is defined and the basic equation to express the variation of load voltage magnitude with the variation of its dynamic equivalent impedance and that of power per unit impedance is derived.

定义了单位阻抗功率的新概念，推导了电压幅值随其等值阻抗和单位阻抗功率变化而变化的基本方程式。

In the paper, an algebraic reconstruction algorithm based on magnetic resonance electrical impedance tomography was presented for 3-dimensional (3D) electrical impedance tomography, especially to image the 3D continuous impedance distribution of the head tissues.

文章给出了一种基于核磁共振技术的三维阻抗成像重构算法，并将该方法应用于人体头部组织电导率分布重构上。

A new method relying on the Stroh formulism and the theory of the surface impedance tensor was developed to investigate the dynamic instability of interfacial slip waves.The concept of the surface impedance tensor was extended to the case where the wave speed is of a complex value,and the boundary conditions at the frictionally contacting interface were expressed by the surface impedance tensor.Then the boundary value problem was transformed to searching for zeroes of a complex polynomial in the unit circle...

基于Stroh公式和表面阻抗张量理论，提出了研究界面滑移波动态失稳问题的一种新的方法·该方法将表面阻抗张量概念推广到复波速域，并将摩擦接触界面上的边界条件以表面阻抗张量表示·最终将边值问题化归为求解一个复多项式在单位圆内的根·以弹性半空间与刚体平面相对稳态摩擦滑移为例进行了详细的分析，导出了一个4次复特征方程并讨论了方程在单位圆内解的特性，给出了滑移界面波失稳条件的显式解析表达式

According to the studied results at present, the studied objects are mainly thin plate and beam about sound radiation mode, a method computed sound radiation mode of complex structure is presented in this dissertation, according to the results of the previous two chapter, a theoretical method to solve acoustical radiation mode and acoustical radiation efficiency of complex structure by boundary element method and acoustical radiation theory is posed, the acoustical radiation power is expressed as a Hermitian quadratic form, while the radiation modes is determined by general eigenvalue decomposing, and then the radiation efficiency is computed via the orthodoxy of radiation modes with regard to impedance matrix and average velocity matrix; lastly, the validity of the method is proved by pulsating sphere and radiating cube with analytical results. According to results of the form three chapter, the structure sound radiation sensitivity is studied in detail, the sound radiation power of structure can be expressed as positive Hermitian quadratic form, the sound radiation sensitivity can be expressed as two parts by partial differential with respect to design variable, which are sensitivity of boundary velocity and impedance matrix, combined with the theory of FEM and BEM, the structure sound radiation can be translated to the analysis of structure dynamic sensitivity and impedance matrix sensitivity. The theory posted in this dissertation is tested by the FEM software ANSYS and the software AAS programmed by author.

在前几章的基础上，通过结构声辐射的模态理论对结构的声辐射的机理进行了深入地探讨，针对目前声辐射模态的研究对象主要是简单的板和梁类结构，提出了一种计算复杂结构声辐射模态的方法，利用前两章研究所得的结论，将边界元方法与广义特征值的理论结合起来研究了复杂结构的声辐射模态与声辐射效率，先将结构的声辐射功率表示为一个正定的厄米特二(来源：ABb7C论文0909网www.abclunwen.com)次型，运用广义特征值分解求解了复杂结构的声辐射模态，然后利用声辐射模态关于阻抗矩阵与均方速度耦合矩阵的正交性，求解了复杂结构的声辐射效率，最后用具有解析解的脉动球与辐射立方体验证了该方法的有效性。

It usually takes a long time to fill the impedance matrix when using higher-order MoM. To solve this problem, the properties of the impedance matrix elements and the involved integral are investigated. Then it is proposed to take advantage of the symmetry of impedance matrix and the integral table to expedite the impedance matrix filling.

针对高阶矩量法阻抗矩阵填充时间很长的问题，从阻抗矩阵元素本身的性质和积分计算过程入手，提出了应用阻抗矩阵对称性和积分表方法两种加快阻抗矩阵填充的手段。

The one order differential model and convolutional model of impedance formula of amplitude versus offset inversion were established. Impedance inversion formula from AVO was derived based on Bayesian framework. Methods of using Huber function as prior model parameter distribution and covariance matrix from well log as constrains were developed. The P-wave impedance, S-wave impedance and density were calculated by the conjugate gradient algorithm.

为此建立了振幅随偏移距变化波阻抗反演公式的一阶差分模型及褶积模型，推导了基于贝叶斯理论的AVO波阻抗反演公式，给出了采用Huber分布作为模型参数的先验分布及测井数据的参数协方差矩阵作为约束条件的实现方法，并利用共轭梯度法计算了纵、横波阻抗及密度。

Different biases can result in the opposite phase shifts of the impedance with respect to the applied signal. Neutral gas pressure affects the magnitude of the impedance, but does not change the shape of the frequency response curve. In addition, the position of the grid inside the vacuum chamber has little effect on the impedance.

结果显示栅网上的直流偏压对阻抗的影响很大，不同偏压可以使阻抗的频率响应反位相，气压对阻抗的大小有明显影响，但一般不改变频率响应曲线的形状，栅网的位置对阻抗几乎无影响。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了