交替

The technique of boundary-fitted coordinate system is used to overcome the difficulties resulting from the complicated shapes of natural river boundaries;the method of alternating direction implicit finite difference scheme is used to solve the partial differential equations in the transformed plane;and the technique of moving boundary is used to deal with the river bed exposed to water surface.

用适体坐标技术克服天然河道复杂的几何边界给有限差分法所带来的困难；用交替方向隐式有限差分格式求解变换平面上的偏微分方程；用动边界技术处理河床的淹露。

To reduce the large numerical dispersion error for the alternating direction implicit finite-difference time-domain method, an isotropic ADI-FDTD method with low numerical dispersion error was presented.

针对交替方向隐式时域有限差分方法数值色散严重的缺点，提出了一种低数值色散的各向同性ADI-FDTD方法。

Based on the second- and fourth-order compact difference formulas for second-order derivatives and the idea of weighted average, two classes of the alternating direction implicit method are proposed for solving two-dimensional wave equation. The methods are of accuracy O (T^2+h^4) and O (T^4+h^4) respectively. Stability conditions are obtained by Fourier analysis method.

基于二阶微商的四阶紧致差商逼近公式及加权平均思想，提出了数值求解二维波动方程的2种精度分别为O(т^2+h^4)和O(т^4+h^4)的交替方向隐式格式，以及与其相匹配的第一个时间层的同阶离散格式，并且通过Foulier方法分析了格式的稳定性。

This thesis contributed to the comprehensive study of the Finite-Difference Time-Domain method and its application to the numerical computation of radiated electromagnetic fields in switched mode power supplies. The work includes mainly three parts: the study on the performance of PML absorbing boundary condition applied to pseudo low frequency electromagnetic problems; the validation of the FDTD method with PML absorbing boundary conditions and the corresponding computer software based on the numerical study of the electromagnetic field of an electric dipole antenna, and its application to the numerical computation of radiated electromagnetic fields in switched mode power supplies; the development of an improved alternating direction implicit finite-difference time-domain method.

在综合前人工作基础上，本文对时域有限差分法及其在开关电源辐射电磁场数值计算中的应用进行了系统的分析和研究，其核心内容包括：伪低频电磁场数值计算中PML吸收边界条件性能的研究；基于基准问题—电偶极子天线三维辐射电磁场，验证了本文构造的基于PML吸收边界条件的三维FDTD法及其计算软件，并应用于高频开关电源辐射电磁场的数值分析；提出了一种改进的交替方向隐格式时域有限差分法。

State Key Laboratory of Millimeter Waves, Southeast University , Nanjing 210096, ChinaIn this paper, it is proven that the divergence relationship of electric-field and magnetic-field is non-zero even in charge-free regions, when the electric-field and magnetic-field are calculated with Alternating Direction Implicit Finite-Difference Time-Domain method, and the concrete expression of the divergence relationship is derived.

摘要该文证明了即使在无源区域，交替方向隐式时域有限差分法所给出的电磁场量不满足零散度关系，同时推导出了该散度关系的具体表达式。

Calculated the lower limit of abnormal after the plane through the delineation of the contour map of the occurrence and analysis of abnormal findings were as follows: work area on the lithology in terms of more or less divided into two parts, East and West, the western area for the low-resistivity, lithology is metamorphic carbonaceous sandstone or slate, for the emperor in eastern areas, lithology for granite and granite porphyry, quartz vein occurrence in eastern and more, these quartz veins is into the eastern part of the resistivity of the form of alternating high and low.

计算了异常下限值后，通过圈定了平面等值线图上的矿点异常和其它分析得到结论如下：工区就岩性而言大致划分为东西两部分，西部为低阻区，岩性为变质砂岩或炭质板岩，东部为高祖区，岩性为花岗岩及花岗斑岩，东部多赋存石英脉，这些石英脉是的东部电阻率成高低交替的形式。

The alternating group iterative method for the dispersive equation with periodic boundary condition is presented.

给出了求解具有周期边界条件色散方程近似解的交替分组迭代法。

The alternating group iterative method is used to solve the implicit scheme and the Crank-Nicolson scheme of the dispersive equation.

数值试验对色散方程的隐格式与Crank-Nicolson格式分别应用交替分组迭代求解。

Questioner: Is it possible for an entity here on Earth to be so confused as to call both the Confederation and the Orion group in an alternating way, first one, then the other, and then back to the first again?

发问者：一个地球上的实体，是否有可能因同时交替呼求星际联邦与猎户集团而变得混乱，先是前者，再是后者，又回到前者？

Similarly, the acyl-oxygen cleavage of MG mainly occurs at theleast hindered carbonyl group and alternating D,L-PLGA50 wasobtained.

同样，MG单体的开环主要发生在位阻较小的羰基一侧〓，合成了窄分子量分布的聚乳酸-交替-聚乙醇酸共聚物。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失