查询词典 second boundary condition

In this paper,the diagonal Cartesian method simulating the complex boundary, together with thetreatment to wetting-drying dynamic variation of the boundary, is applied into thetwo-dimensional shallow-water flows and sediment transport mathematical modeling,and their governing equations are discretized and solved in diagonal Cartesiancoordinates.

本论文采用斜对角笛卡尔坐标方法对不规则的复杂边界进行模拟，重点处理好干湿动边界的变化，并在斜对角笛卡尔坐标系中进行二维浅水运动的水流泥沙基本控制方程的离散和数值计算求解。

And the devices'properties and improve the properties to prepare the artificial boundary. The bi-epitaxial YBCO superconducting film with 45°grain boundary in a-b plane was made for the first time in China in this article by magnetic sputtering instrument that was designed and fabricated by ourselves. The x-ray θ～ 2θ scan 、Ф scan、rocking curve、non-symmetry diffraction and SEM、 TEM、AES etc. were utilized in the study.

为此，本工作采用自行设计制造的全金属密封超高真空磁控溅射设备，利用x射线θ～2θ扫描、Ф扫描、摇摆曲线、非对称衍射及SEM、TEM、AES等分析测试手段，在国内首次、也是至今唯一的一家，制得a—b平面内具有45°人工晶界的双外延YBCO超导薄膜，并进而得到双外延晶界Josephson结。

The complex variable boundary element-free method is a direct numerical method of the meshless method of boundary integral equation.

复变量边界无单元法是边界积分方程的无网格方法的直接列式法，容易引入边界条件，且具有更高的精度。

By using the spatial finite sine and cosine transform, and the temporal Laplace transform, the existence of the analytic solutions of its initial-boundary problems in a boundedspace domain with Dirichlet and Neumann boundary conditions is derived.

利用空间有限的sine或cosine变换及时间Laplace变换，给出了该方程有限区间上带Dirichlet和Neumann边界条件的两类初边值问题的解析解。

Compared with the same wave problems with conventional Dirichlet boundary conditions, the absorbing boundary conditions can reduce the numerical reflection on boundaries and avoid solution distortion. In addition, the central differences method is economic in memory requirement and computing time compared with implicit integral method.

结果表明：该解法在空间上具有谱精度，在时间上达到二阶精度；与第一类边界条件相比，吸收边界有效地削弱了边界上的数值反射，避免了解的失真；使用中心差分的时间积分方法同隐式积分方法相比，适合波的传播特性，避免了矩阵求逆运算，并且占用的计算机内存小。

The finite dimension approximating solution for initial-boundary value problem of coupling nonlinear system of hyperbolic equation is constructed by orthogonal basis of characteristic value sequence of the Laplace operator in the Dirichlet boundary conditions.

以Laplace算子在Dirichlet条件下的特徵值序列为正交基底构造耦合非线性双曲型方程组初边值问题的有限维近似逼近解，证明该逼近解的一致收敛性。

Laplace equation; Dirichlet problem;Direct boundary integral equation; Fredholm integral equation of the first kind;Galerkin boundary element method

论文导师祝家麟，论文学位硕士，论文专业计算数学论文单位重庆大学，点击次数 2，论文页数 73页File Size1023k

The method involves an iterative procedure, which incrementally flattens a 3D triangular mesh by region growing and obtains a parameterization with free boundary. The result is then converted to a parameterization with regular boundary by conformal mapping. Our method accounts for both the angle and area distortion during parameterization, it yields a parameterization with less global distortion and no triangular flipping.

采用区域增长算法逐层展平空间三角网格，得到空间三角网格曲面的自由边界的参数化结果，并利用保形变换将自由边界的参数化结果变换为规则边界的参数化结果；同时兼顾了参数化的角度变形和面积变形，使得参数化结果具有整体变形较小的特点，并能够避免三角形折叠的现象。

It is concluded that the inversion of unknown boundary data is more effective when the Cauchy data are given more precisely and are distributed on the whole boundary more diversely.

由数值的结论，我们认为只要柯西资料给定的越准确，并且在全边界上给定的越分散，则会有越好的结果。

According to the boundary relations of the electromagnetic field, and based on the phenomena of double refraction and double reflection in crystals, the reflectivity and transmissivity are deduced at boundary when an extraordinary beam is incident from an isotropic medium upon a crystal or from a crystal to an isotropic medium with optical ax.

为分析非常偏振光在晶体表面的能量损耗，给出一种求解反射率和透射率的方法，即根据电磁场的边值关系以及晶体的双折射和双反射现象，求解晶体光轴在入射面内时，非常偏振光从各向同性介质入射到晶体和从晶体出射到各向同性介质两种情况的反射率和透射率的方法，并给出反射率和透射率的解析解，同时得到对于晶体光轴在入射面内的情况，光轴的取向对非常偏振光反射率的大小几乎没有影响，但对产生全反射的临界角θc影响较大的结论。

Aquatic or marsh-growing fern allies; known to have existed since the Cenozoic; sometimes included in Lycopodiales.

生活于水中或湿地的蕨类；从新生代生存至今；有时归于石松目之中。

The engine was uprated from a 90hp Franklin to a 125hp Lycoming.

改良过的引擎是从90hp到125hp莱康明富兰克林。