边界条件

The full space calculation model, which suits for the asymmetric structure sometimes even including air below the surface of medium, can enable simulative result to approach real one. The FDTD algorithm based on the mixed ABCs is proper to calculate the transmission line where the electromagnetic wave is transmitted in order to send electromagnetic energy along central conductor. The calculation efficiency will be raised if the PML absorbing boundary condition is set on both planes of transmitting direction and so is the MUR two-order absorbing boundary condition in the other planes.

全空间计算模型是适合所有的不对称结构的待研究体的，而且包括了介质下面的空气部分，使仿真更加的接近实验真实情况；基于MUR-PML混合吸收边界条件的时域有限差分法非常适合计算传输线这种结构，因为传输线是传送电磁波的，电磁能量主要是沿着中心导带行进，因此在两个传输端面上设置PML完全匹配层吸收边界条件，在其他面上设置MUR二阶吸收边界条件，会大大提高计算效率，而且计算结果与XFDTD仿真软件计算结果相比较，基本趋于一致。

In the third part, we discuss a simple class of Sturm-Liouville problems with Dirichlet boundary condition in the first boundary condition and an affine function in the second one.

第三部分我们讨论了一类参数边界条件的Sturm-Liouville问题，其第一边界条件为Dirichlet条件，第二个边界条件为特征值参数的线性函数。

For the Riemann boundary value problems for the first order elliptic systems , we translates them to equivalent singular integral equations and proves the existence of the solution to the discussed problems under some assumptions by means of generalized analytic function theory , singular integral equation theory , contract principle or generaliezed contract principle ; For the Riemann-Hilbert boundary value problems for the first order elliptic systems , we proves the problems solvable under some assumptions by means of generalized analytic function theory , Cauchy integral formula , function theoretic approaches and fixed point theorem ; the boundary element method for the Riemann-Hilbert boundary value problems for the generalized analytic function , we obtains the boundary integral equations by means of the generalized Cauchy integral formula of the generalized analytic function , introducing Cauchy principal value integration , dispersing the boundary of the area , and we obtains the solution to the problems using the boundary conditions .

对于一阶椭圆型方程组的Riemann边值问题，是通过把它们转化为与原问题等价的奇异积分方程，利用广义解析函数理论、奇异积分方程理论、压缩原理或广义压缩原理，证明在某些假设条件下所讨论问题的解的存在性；对于一阶椭圆型方程组的Riemann-Hilbert边值问题，利用广义解析函数理论、Cauchy积分公式、函数论方法和不动点原理，证明在某些假设条件下所讨论问题的可解性；广义解析函数的Riemann-Hilbert边值问题的边界元方法是利用广义解析函数的广义Cauchy积分公式，引入Cauchy主值积分，通过对区域边界的离散化，得到边界积分方程，再利用边界条件得到问题的解。

Spectral element methods for partial differencial equation is introduced in this study from viewpoint of the collocation approximation of Chebyshev polynomial. Wave Equation and its space discretization are deduced. Two time integral methods, central difference method and implicit Newmark method, are introduced, and their stability and applicability are also discussed in some details. The significance of absorbing boundary conditions in spectral element methods for Aeroacoustics is explained, and Clayton-Engquist-Majda absorbing boundary conditions is emphasized and introduced, then the discrete scheme of this boundary conditions is deduced and applied to spectral element methods for wave equation.

本文从Chebyshev多项式逼近理论出发，详细介绍了谱元方法求解偏微分方程的过程；推导了流体中的声波动方程并在空间上对其进行了谱元离散；详细讨论了两种时间积分方法──中心差分法和Newmark方法，分析了它们的稳定性条件，并从理论上对比了两种方法的优缺点和适用范围；将吸收边界条件推广应用于谱元方法求解气动声学问题中，重点介绍了Clayton-Engquist-Majda吸收边界条件的原理和公式，推导了该吸收边界条件的变分形式，并将其引入波动方程的离散形式中。

The phase of optical wave can be recovered by the intensity transport equation under the paraxial approximation For the optical system with diffraction limit, it is difficult to get the boundary radical slope of phase and sample in the circular domain boundary when using the intensity transport equation to recover the phase, consequently, we reviewed an algorithm mentioned in the reference ［4］, namely, the equation, computation domain and boundary condition are changed, then the phase is reconstructed by the multigrid method and corrected at last Moreover, the experiment system is set to testify the algorithm, and the recovered phase from the intensity data detected by CCD is compared with the result from phase retrieval algorithm, it is found that the phase reconstruction error can reach 017 λ in the case of non-uniform intensity distribution, as a result, the method is suitable for the phase recovery with low wavefront sensing accuracy.

在傍轴近似条件下，可以利用光强传播方程对畸变波前进行相位恢复。对于衍射受限的光学系统，很难获得相位的边界径向斜率值作为边界条件，此外，要获得精确的圆域边界采样值也并非易事。为了克服上述困难，进一步研究了相位恢复改进方法，即改变了方程的表示形式、计算区域和边界条件，并用多重网格法进行求解获得重构相位，最后再将其修正。为了验证算法的精确性，搭建了实验系统对算法进行实验验证，将由CCD探测的光强分布进行计算得到的相位分布与相位恢复算法的结果进行比较，证明在光强分布非均匀的情况下，该方法恢复的相位均方根误差能够达到017 λ，可以适用于波前传感精度要求不是很高的相位恢复。标签自适应光学相位恢复相位修正光强传播方程 adaptive optics phase retrieval phase correction intensity transport equation

The author compares the effects of Dirichlet boundary condition and attenuation one on artificial boundary with that on transmitting boundary, so does the absorption effects, the author also demonstrates the advantage of transmitting boundary.

文中还就刚性边界条件、衰减边界条件对人工边界的影响及吸收效果与透射边界作了对比，验证了透射边界的优越性。

We can not apply Galerkin methods with radial basis functions to the first boundary value problem (the Dirichlet boundary value problem) of the second-order elliptic equation, because it requires that the approximate functions should fit the essential boundary condition, while the spaces spanned by the radial basis functions fails to satisfy this kind of boundary condition, and it is the same for the higher-order elliptic equation.

我们不能直接应用这样的无网格算法求解二阶椭圆型方程的第一类边值问题(Dirichlet边值问题)，因为第一类边界条件是本质边界条件(对二阶椭圆型方程为Dirichlet边界条件)，而径向基函数的支集通常是全空间，由它们所生成的近似函数空间一般不满足这样的条件。

The classical overlapping Schwarz methods try to transport boundary information by exchanging message on the artificial boundaries. However because of taking Dirichlet conditions as the transmission conditions, which makes the solution reflect when across the artificial boundaries, classical overlapping Schwarz methods converge very slowly—suppose the overlapping domains take a little percentage.

人们很早就认识到，在Schwarz方法中可以采用其它的内边界条件—如Robin条件来代替Dirichlet内边界条件，而且也注意到如果参数选取合适，那么这些内边界条件可以大大加快Schwarz方法的收敛速度。

This method allows for a more accurate processing of boundary condition on the semiconductor layer in XLPE cable of stator winding than the standard finite element, so that the interlaminated issue of boundary condition on interface can be avoided. A general algorithm is applied to deal with both the Dirichlet and the periodic boundary condition in 2D or 3D magnetic field problem.

提出了用有限元法计算磁场问题时周期性边界条件和第一类边界条件的统一处理方法，利用该方法在不改变代数方程组阶数、保持系数矩阵性质不变和带宽基本不变的条件下，使两种强加边界条件能同时处理，简化了程序编制，并与寻址方法相结合，提高了计算速度。

The transmission of heat differential equation for the heat conduction process of thermoelectric module was derived And the solution with the first kind boundary conditions under the influence of Thomson effect and the solution with the third kind boundary conditions without the influence of Thomson effect was obtained.

在假设热电制冷的热端温度固定的条件下，得出热电制冷器在不同工况下的最佳工作参数并进一步求得在三类边界条件下的最佳工作参数；导出了电偶臂在电与热的偶合作用下传热微分方程，并对其进行解析求解：在考虑汤姆逊效应的影响下得出一类跟三类边界条件下传热方程的解析解，在忽略汤姆逊效应的影响下得出二类跟三类相的边界条件下传热方程的解析解。

He is the most remarkable man that I have ever known.

他是我知道的人中最值得注意的人。

Increased appearance of lymphocele was noticed in patients with diabetic nephropathy, congenital malformations of the urinary tract, and inflammatory diseases, including glomerulopathy and extraglomerular ones, after high-voltage radiotherapy and after removal of the renal graft.

经过高压放射疗法和切除移植肾后，在糖尿病肾病患者、泌尿系统先天性畸形患者和炎症患者身上发现淋巴囊肿有所增加，包括肾小球病和球外疾病等。