基于逐点扫描的波前数据重构

提出一种对孔径网格逐点扫描重构波前的方法。该方法基于Hudgin模型,在孔径阵列的对角线上选取P个已知参考点。每个参考点都按行扫描计算得到一个波面,按列扫描又得到一个波面,这样P个参考点得到2P个波面,对这2P个波面求平均即为重构波面。对如何选择参考点进行了介绍,并说明选择高低坐标对称搭配的参考点为佳。建立了波面相位误差估算模型,并从理论上推出波面重构误差随参考点的增加而改善。对新方法进行了实验证验,与传统的矩阵求逆方法进行比较,结果表明,两种方法效果相当,但新方法计算量更小,具有较强的实用性。     

基于MATLAB对二维混合边界静电场域的分析

本文分析了有限差分法的原理与概念,讨论了电磁场问题涉及3种类型的边界条件,采用有限差分数值计算分析边界问题,对二维混合型边界静电场进行分析,用MATLAB编程计算差分方程,并将超松弛迭代法引入到差分方程的计算,并与简单迭代方法进行比较,同样的计算精度下采用超松弛法不仅节省存储空间,而且加快了收敛速度。通过计算可以看出MATLAB在解决实际的工程和数学问题中,具有使用更为简便、语句功能更强的特点,能直观地演示二维混合边界静电场的电势分布图和场强立体分布图。     

二值加权正交迭代相机位姿估计算法

在相机位姿估计算法的实际应用中,由于2D像点与3D参考点的错误匹配,参考点中往往含有异常值。针对现有算法抗异常值能力较弱的问题,提出了一种基于正交迭代的二值加权算法。该算法在正交迭代算法的基础上,引入包含两个阈值的加权系统来衡量参考点的可靠性。选取重投影误差的四分位数中的最大值作为阈值之一,另外引入一个与重投影误差和焦距相关的阈值来加速异常值比例较低时的收敛速度。最终选取两阈值的最大值对目标函数进行二值加权,降低了异常值对估计结果的影响。实验表明,该方法提升了正交迭代算法的抗异常值能力,具有较强的鲁棒性。     

有限差分法在静态电磁场计算中的应用

介绍了采用有限差分法求解特殊边界条件下二维静态电场问题,并将电磁场数值方法的思想体现在处理过程中。对场域中的电势、电位进行了具体的分析和计算,给出了用C语言进行编程计算得到场量数据的流程图,最后利用MATLAB强大的绘图功能对结果进行可视化。由文章研究问题所得图形结果可以清晰的看出静电场中的电势线及电场线的分布,同时也验证了电场线与等电位线相互垂直,以及电势在媒质分界面连续的经典理论。     

基于ANSYS静电除尘器中的电场分析

基于除尘器的高压静电除尘原理,运用ANSYS软件对静电场进行求解。本文主要通过电势云图,场强云图对静电除尘器内的电场特性进行简要的分析。根据仿真可以得到静电场中各个节点电位、电场强度分布情况。     

白光干涉法三维面型重构仿真研究

采用Twyman光路结构和LED为光源进行白光干涉三维测量,对干涉图像及元件面型的重构算法进行了仿真研究。使用Matlab软件,选取了两种面型结构函数,仿真得出重构的面型,选取5个参考点进行了对比。研究结果表明,白光干涉测量具有高精度、测量时间短、相对误差小于0.5%。     

用MATLAB解决电磁学中的静电场问题

在研究电磁学中的电场问题时,静电场的概念抽象且不易被学生理解,而且在实验室里很难实现它的理想化模型。本文运用数学软件MATLAB模拟出真空中自由电荷、几种带电导体产生的静电场场强和电势分布图,使其更加形象地、容易地被理解和接受,方便教师教学和学生学习。     

二维寄生电容参数的对偶离散几何法提取

寄生电容参数提取是集成电路领域的关键课题,也是典型的静电场问题之一。通过研究电磁场对偶离散几何法, 探讨在二维非结构化网格离散空间上相应的寄生电容提取算法, 其中重点考察其对偶特性以及能量互补特性。基于该特性,同时采用对偶的两种方法能够有效地消除网格离散带来的误差,比采用单一方法更快地逼近真实解,从而可发展出静电场能量快速算法。并从理论与实例两方面将其与对偶有限元法实施分析对比。离散几何法采用对偶两套网格上的标量电势作为未知量,具有简单的形式与良好的精度,有望成为相关领域的一种主流方法。     

基于光滑有限元法的屏蔽微带线静电场研究

传统有限元方法(FEM)在预测屏蔽微带线横截面电势时存在效率低、精度差的缺陷，针对这种情况，构造了一种屏蔽微带线电势模拟的光滑有限元(S-FEM)数值模型。基于三角形背景网格的边、节点构建光滑域，依托梯度光滑技术(GST)对电势梯度进行光滑处理，最后根据光滑Galerkin弱形式得到系统离散方程。应用构造方法对屏蔽单微带线、屏蔽耦合微带线静电场进行了模拟，结果表明:相比FEM,S-FEM能有效提升计算效率与精度，在屏蔽微带线的设计研究中具有一定应用价值。     

CATV反向通道的调试

在有线电视系统引入ＨＦＣ后 ,双向传输变得较容易。反向通道的设计和调整与正向通道有很大不同 ,本文着重介绍如何调整反向通道。1　两个基本概念“参考点”和“峰均比”是ＨＦＣ双向网中反向通道所特有的两个基本概念。1.1　单位增益和参考点对于正向通道的设计和调试 ,一般以放大器输出口作为参考点。电缆和无源器件的衰减等于放大器的增益 ,从前一个放大器输出口到后一个放大器输出口 ,其衰减或增益为零 ,称为单位增益。反向通道有两种参考点可以选择 ,即以放大器上行放大模块输入为参考点和以放大器下行输出端口(上行输入端口 )作为参…     

有限差分法求解静电场问题

简介了有限差分法（FDM）的起源,讨论其在静电场求解中的应用.以铝电解槽物理模型为例,采用FDM对其场域进行离散,使用MATLAB和C求解了各节点的电位.由此,绘制了整个场域的等位线和电场强度矢量分布.同时,讨论了加速收敛因子对超松弛迭代算法迭代速度的影响,以及具有正弦边界条件下的电场分布.     

用 Matlab 实现恒定电场的可视化

用静电比拟方法将恒定电场问题转化为静电场问题后,可用Matlab求解并实现可视化。电力线图能反映场的宏观概况和细节分布,具有清晰的物理含义。Matlab绘制电力线图需要指定准确的起点,简单问题可通过分析对称性直接得到电力线的起点,对称性差的问题要根据电场公式迭代计算确定电力线起点。数字图像处理技术可用来增强恒定电场的图形效果。可视化教学能为抽象电磁理论带来直观性,从而提升教学效果。     

Complex images of a point charge in rectangular conducting planes

The exact images of a point charge in rectangular conducting planes are discretely located on an infinite plane, making it difficult to compute the electrostatic field rapidly. In the paper, a complex image theory for the electrostatic problem in rectangular conducting planes is investigated. The research shows that only a few complex images are used to replace the countless exact images, but the error is less than 0.2% when they are utilized to compute the electrostatic potential functions, and the execution time is greatly reduced     

Solution of Some Electrostatic Potential Problems Involving Spherical Conductors: A Dual Series Approach

The solution of several electrostatic potential problems involving open spherical perfectly conducting shells is presented in the context of the dual series equations method. These equations are a consequence of mixed boundary conditions imposed on the electric potential and field. A solution is given for the dual series equations corresponding to two concentric spherical shells, one of which has a circular aperture. The aperture dipole moment, the capacity, and field penetration of some electrostatic devices are also calculated.     

对现行电磁场教材中电位的分界面衔接条件推导问题的商榷

分析了静电场中电位的分界面衔接条件,指出多本《电磁场》教材在推导过程中存在的问题,并提出了相应的商榷意见,以供教学参考。     

Effect of inelastic processes on the self-consistent potential in the resonant-tunneling diode

The self-consistent electrostatic potential of a biased resonant-tunneling diode is examined using a quantum kinetic theory of open systems. The potential obtained is sensitively dependent upon the assumed magnitude of inelastic processes within the device and its contacts. If inelastic processes are neglected one finds a solution with an unphysically large electric field at one boundary, which is also obtained from an analysis using Schroedinger's equation. Including inelastic processes within the device permits screening of the electric field, leading to a much more credible potential. Furthermore, if the mean velocity of the electron distributions on the boundaries is allowed to shift in response to the boundary electric field, the resulting potential profiles closely resemble those obtained from simple screening theory.     

Reduction of a parabolic problem to a 2D problem and a phantom

A parabolic variant of the 3D electrostatic problem is reduced to a plane (2D) problem. The results are used in the analysis of the effect of phantom shape and size on the electric field that is induced in the phantom by an external source.     

A data complementary method for thunderstorm point charge localization based on atmospheric electric field apparatus array group

Data loss or distortion causes adverse effects on the accuracy and stability of the thunderstorm point charge localization. To solve this problem, we propose a data complementary method based on the atmospheric electric field apparatus array group. The electric field component measurement model of the atmospheric electric field apparatus is established, and the orientation parameters of the thunderstorm point charge are defined. Based on the mirror method, the thunderstorm point charge coordinates are obtained by using the potential distribution formulas. To test the validity of the basic algorithm, the electric field component measurement error and the localization accuracy are studied. Besides the azimuth angle and the elevation angle, the localization parameters also include the distance from the apparatus to the thunderstorm cloud. Based on a primary electric field apparatus, we establish the array group of apparatuses. Based on this, the data measured by each apparatus is complementarily processed to regain the thunderstorm point charge position. The results show that, compared with the radar map data, this method can accurately reflect the location of the thunderstorm point charge, and has a better localization effect. Additionally, several observation results during thunderstorm weather have been presented.     

Electrostatic correction of the chromatic and of the spherical aberration of charged-particle lenses (part I).

A feasible electrostatic corrector (ECO) is outlined and the principle of the electrostatic correction is elucidated by means of a light-optical analogue. The ECO compensates for the chromatic and the spherical aberration of charged-particle lenses and reduces the resolution limit of a special LVSEM (low-voltage scanning electron microscope) from 6 nm to 1.4 nm. The geometry of the electrodes of the corrector is optimized with respect to the chromatic correction, the maximum strength of the electric field, and the residual higher-order aberrations which limit the resolution. In addition the stability criteria of the electric power supplies are discussed in detail.