共形PML下三维电磁散射矢量有限元计算

共形完全匹配层吸收边界能满足复杂构型散射体的几何外形要求,又具有良好的电磁波吸收特性,大幅度减少了散射区网格的数量,达到节省计算机存储量的目的。在ANSYS采用的六面体矢量单元的基础上,对矢量基函数作了一些增强正交性的修改,使其同时具备采样点正交性和积分正交性,得到了一种新的正交增强六面体矢量单元;这种新单元能增强系统矩阵的对角占优特性,加快系统方程组的求解速度。数值算例表明,在共形完全匹配层条件下,采用新的正交增强矢量单元进行三维电磁散射计算既能减少计算存储量,又能提高计算速度和精度,具有工程应用价值。     

一种新的材料微结构电磁场效应数值模拟方法

为了定量揭示材料微结构与入射电磁波引起的材料内电磁场效应之间的内在关联性,借助可以表征能量流动方向和大小的Poynting矢量,通过程序设计结合有限元数值模拟的方法实现了材料微结构电磁场效应的计算。建立了材料微结构电磁场效应数值分析有限元模型。在数值计算中,将Poynting矢量正交分解为三个不同方向分量,计算了材料微结构的吸收、透射和波源方向反射效应;根据Poynting矢量在反射方向的分量,计算了任意反射方向的反射效应。研究方法对任意微结构均具有适用性。     

基于OpenCL的GPU加速三维时域有限差分电磁场仿真算法研究

提出了一种基于开放运算语言（OpenCL）的GPU加速三维时域有限差分（FDTD）电磁场仿真计算的方法．该方法利用图形处理单元（GPU）的并行处理特性并结合OpenCL接口标准实现了时域卷积完全匹配层（CPML）吸收边界条件的三维FDTD的高性能加速计算．首先设置FDTD仿真参数并动态申请内存空间,然后初始化OpenCL的计算参数,对三维电磁模型基于OpenCL进行FDTD加速仿真．本方法显著提升了FDTD电磁场仿真速度,与利用CPU计算相比速度提升可达5-8倍,且具有CPML吸收边界条件,可以模拟电磁波在自由空间的传播;基于OpenCL编译的语言程序可以运行在CPU或GPU硬件上,并可充分发挥多核CPU的并行计算能力,使得FDTD电磁场仿真具有更广泛的实际应用．     

全波场地震波数值模拟中的边界处理实践研究

在用有限差分法或有限元法模拟无界区域中的波动时,需要对计算区域的边界做特殊处理,以消除由于把地震波的传播设定在有限区域而产生的边界反射。为了这一目的,人们研究出了多种人工边界处理方法,完全匹配层（PML）吸收边界条件就是理想的方法之一,现已被广泛应用。本文将PML吸收边界条件应用于全波场地震波的数值模拟,数值计算实验表明,对qP波,匹配层的厚度为5个网格间距即可达到要求,而对qSV波与qSH波,为达到理想的吸收效果,匹配层的厚度应当增大,当厚度为13个网格间距时达到了理想的吸收效果。     

数字系统故障诊断的矢量方法

本文从纠错码的理论出发,利用图的矩阵表示法,讨论了数字系统的故障诊断问题。文中根据 PMC 模型,通过引入故障矢量,给出了一个矢量能成为系统故障矢量的充分必要条件,并证明了其正确性。然后,在此基础上,提出了一种有启发性的系统诊断算法。     

基于高性能光电材料和核酸信号放大策略的光致电化学生物传感器概述

1839年Edmond Becquerel首次发现了光电效应，自此光致电化学（photoelectrochemical,PEC）蓬勃发展。通常情况下，PEC过程是指有机/无机光电活性材料在光照射下吸收光子，电荷随之发生分离和转移，实现光-电转换过程，界面处产生的电子-空穴对（e--h+）将引起分子或离子的氧化还原反应。光致电化学与生物分析的结合开创了PEC生物分析的新兴领域，PEC生物分析主要包含两个关键要素：光电活性材料和生物识别元件，其中，光电活性材料用于产生检测信号，生物识别元件主要为酶、抗体和核酸等，它与检测目标物相关。PEC生物分析原理为识别元件与其相应的目标物之间发生生物相互作用，引起光电流/光电压的变化，该过程以光作为输入信号，电流/电压作为检测信号，这种不同的能量形式也赋予PEC生物分析低的背景信号和较高的检测灵敏度。目前，PEC生物传感在疾病早期诊断、环境污染物监测、食品安全分析等方面显现出潜在的应用前景。而PEC生物传感器的检测性能很大程度受到材料光电性能的影响，因此，提高材料光电转换和载流子迁移效率是有效提高传感器性能的关键。另一方面，待检测目标物浓度一般为痕量甚...     

测定有机金属化合物的传感器

用于有机金属化合物测定的传感器，包含：在要分析的样品中不溶的无机、有机或聚合载体；指示剂，与有机金属化合物可逆反应，其反应产物在150—1500nm范围内有特征吸收、反射或发射光谱带，并且被物理包埋、吸附、吸收、溶解或者以静电或共价方式化学结合于载体；和光学传感器，在特征波长处测量功能载体的吸收、反射或发射并将其换算为溶液中存在的有机金属化合物的浓度。还涉及在线使用上述传感器测定有机金属化合物浓度的方法。     

今天是高德纳的生日

如下图所示，用钢化玻璃制成的鱼缸，左边是鱼缸的正视图，右边是侧视图。鱼缸的底面为长方形，长为n个单位，宽为1个单位。鱼缸中放置了包括左右边界的n＋1个垂直于底面的玻璃隔板，每个隔板都与左右边界的两个侧面平行，两隔板间距为1。假定前后两个侧面足够高，     

基于边界匹配的增强多权重差错掩盖方法研究

提出了一种基于边界匹配的增强多权重差错掩盖算法,通过受损宏块周围时空域相邻宏块的相关信息在增强候选运动矢量集中进行运动矢量选取,采用多权重的边界匹配方法使之在物体边界处能够获得更准确的运动矢量,并专门对连续图像片丢失或整帧丢失的情况进行时域掩盖处理。基于H．26L的仿真实验表明,该方法可有效地抑制视频差错的扩散,取得较好的差错掩盖效果。     

基于边界匹配的增强多权重差错掩盖方法研究*

提出了一种基于边界匹配的增强多权重差错掩盖算法,通过受损宏块周围时空域相邻宏块的相关信息在增强候选运动矢量集中进行运动矢量选取,采用多权重的边界匹配方法使之在物体边界处能够获得更准确的运动矢量,并专门对连续图像片丢失或整帧丢失的情况进行时域掩盖处理。基于H.26L的仿真实验表明,该方法可有效地抑制视频差错的扩散,取得较好的差错掩盖效果。     

Application of CPML to truncate the open boundaries of cylindrical waveguides in 2.5-dimensional problems

1 Introduction Very strong nonlinear interactions can occur between the electron beam and electro-magnetic wave in the generation of HPM sources, and it is very expensive and requires very long time to design the HPM devices experimentally, so the computer simulation is often and widely used to design the HPM devices. The most widely used numerical technique is the PIC (particle-in-cell) method[1]. Based on this method, some full elec-tromagnetic PIC codes have been developed in the Unit…     

基于正交轨迹的共形PML数值仿真方法

从材料的观点看,完全匹配层是各向异性的介质.场在完全匹配层遵从麦克斯韦方程.通过设计磁导率和介电常数张量参数来实现任意形状的共形完全匹配层.为匹配层动态稳定,可应用二维正交轨迹网格和FDTD方法实现了数值共形完全匹配层仿真,数值仿真结果表明基于正交轨迹网格的共形完全匹配层为一个共形FDTD或FEM方法提供了一个有效地吸收边界条件.     

FDTD方法吸收边界条件的研究及应用

用时域有限差分法(FDTD)求解电磁散射问题中,吸收边界条件的设置起着关键性作用.通过时间和空间上的递推算法对时域有限差分法中的两种吸收边界条件:Mur吸收边界条件和完全匹配层(PML)的吸收效果进行了比较和分析.同时,引入参数对PML的差分方程进行了优化,避免了将电磁场分裂为两个分量进行计算,进而降低了计算内存开销.实验结果证明PML具有更优越的吸收性能.最后,在FDTD算法中应用PML吸收层对一圆柱形导体的雷达散射截面积(RCS)进行数值仿真,验证了FDTD算法在计算雷达散射截面积(RCS)上的有效性.     

Unconditionally stable higher order perfectly matched layer applied to terminate anisotropic magnetized plasma

An effective and efficient absorbing boundary condition applied to terminate anisotropic magnetized plasma is proposed in this article. As its mathematical derivations are based on the high order perfectly matched layer (HO‐PML) and Crank‐Nicolson finite‐difference time‐domain method, it has the advantages of reducing late‐time reflections, attenuating evanescent waves, absorbing low‐frequency propagation waves and overcoming the Courant‐Friedrichs‐Levy condition. To validate the efficiency and effectiveness of the proposed HO‐PML, a ridge waveguide model composed of vacuum and the anisotropic magnetized plasma, a dielectric waveguide model composed of the dielectric and the anisotropic magnetized plasma are employed. The numerical results show that the proposal can not only maintain the stability of the algorithm with the increment of the time step but also further enhance the absorbing performance.     

Implementation of convolutional perfectly matched layer for three‐dimensional hybrid implicit‐explicit finite‐difference time‐domain method

The hybrid implicit‐explicit (HIE) finite‐difference time‐domain (FDTD) method with the convolutional perfectly matched layer (CPML) is extended to a full three‐dimensional scheme in this article. To demonstrate the application of the CPML better, the entire derivation process is presented, in which the fine scale structure is changed from y‐direction to z‐direction of the propagation innovatively. The numerical examples are adopted to verify the efficiency and accuracy of the proposed method. Numerical results show that the HIE‐FDTD with CPML truncation has the similar relative reflection error with the FDTD with CPML method, but it is much better than the methods with Mur absorbing boundary. Although Courant‐Friedrich‐Levy number climbs to 8, the maximum relative error of the proposed HIE‐CPML remains more below than ?71 dB, and CPU time is nearly 72.1% less than the FDTD‐CPML. As an example, a low‐pass filter is simulated by using the FDTD‐CPML and HIE‐CPML methods. The curves obtained are highly fitted between two methods; the maximum errors are lower than ?79 dB. Furthermore, the CPU time saved much more, accounting for only 26.8% of the FDTD‐CPML method while the same example simulated.     

A one‐step leapfrog HIE‐FDTD method for rotationally symmetric structures

In this work, they propose a one‐step leapfrog hybrid implicit‐explicit finite‐difference time‐domain (HIE‐FDTD) method for body‐of‐revolution (BOR). Meanwhile, its Convolutional Perfect Matched Layer (CPML) absorbing boundary condition is implemented. In this method, the implicit difference is applied in the angular direction. All the resultant updating equations are still explicit. However, the stability condition of the proposed method is relaxed. The analytical analysis shows that its time step is only determined by the smaller one of spatial increments Δρ and Δz. A scattering example is provided to demonstrate the new algorithm. At the same time, the relative of reflection error of the CPML is given with comparisons of Mur.     

On the Accuracy and Stability of the Perfectly Matched Layer in Transient Waveguides

Energy transmitted along a waveguide decays less rapidly than in an unbounded medium. In this paper we study the efficiency of a PML in a time-dependent waveguide governed by the scalar wave equation. A straight forward application of a Neumann boundary condition can degrade accuracy in computations. To ensure accuracy, we propose extensions of the boundary condition to an auxiliary variable in the PML. We also present analysis proving stability of the constant coefficient PML, and energy estimates for the variable coefficients case. In the discrete setting, the modified boundary conditions are crucial in deriving discrete energy estimates analogous to the continuous energy estimates. Numerical stability and convergence of our numerical method follows. Finally we give a number of numerical examples, illustrating the stability of the layer and the high order accuracy of our proposed boundary conditions.     

An optical target to eliminate impinging light in a light scattering simulation

Based on the Convolutional perfectly matched layers (CPML) absorbing boundary condition algorithm that is implemented at the outer boundary of a light scattering simulation, we propose a numerical target that can eliminate light impinging upon it from arbitrary directions. To model light propagation through random media to a specific position, elimination of light reaching the target position is necessary to prevent further reverberation through the simulation space and become a source of noise. Various factors that affect the performance of the optical target are analyzed, including shape of the wavefront and alignment of the impinging light. Simulation results show that incident light can be most effectively eliminated for incident wavefront normally impinging upon the optical target.     

单极天线的计算机仿真设计

aa输入阻抗,在PML边界条件采用指数差分的形式,减少了误差,与文献比较,获得比较好的结果。