查询词典 boundary collocation

Coordinate sequence method is made up of the instruct information of polygon boundary x, y coordinate. It is the easiest polygon vector encoding method. The file structure of this method is easy, but because of the polygon boundary has stored two times, it will produce data redundancy, moreover, short of neighbor threshold information; Tree index encoding method make all the boundary points digitizing, store the coordinate sequence, connect the point index to boundary line, and then connect the line index to other polygons, so as to the tree index structure has came into being. It eliminates neighbor polygons boundary data redundancy problems; Topology structure encoding method is a method which by setting up a complete topology relationship structure, resolve the neighbor threshold and island information process problem. However, it makes arithmetic more complicated and makes database bigger.

坐标序列法是由多边形边界的x，y坐标对集合及说明信息组成，是最简单的一种多边形矢量编码法，文件结构简单，但多边形边界被存储两次产生数据冗余，而且缺少邻域信息；树状索引编码法是将所有边界点进行数字化，顺序存储坐标对，由点索引与边界线号相联系，以线索引与各多边形相联系，形成树状索引结构，消除了相邻多边形边界数据冗余问题；拓扑结构编码法是通过建立一个完整的拓扑关系结构，彻底解决邻域和岛状信息处理问题的方法，但增加了算法的复杂性和数据库的大小。

The main creating aspects are finding and clarify such a fundamental physical process that the grain boundaries emit vacancies under compressive stress to induce solute non-equilibrium grain boundary dilution and absorb vacancies under tensile stress to induce non-equilibrium grain boundary segregation, formulizing the structural equations and the composition equations in force equilibrium in grain bounary region to describe this physical processes and the kinetic equations for non-equilibrium grain boundary segregation under tensile stress, calculating the modulus in grain boundary region from the expermental data of grain bounday segregation using the structure and coposition equations and calculating the diffusion coefficients of vacancy-solute atom complexes using the kinetic equation simulating the experimental results of grain boundary segregation.

本项目的主要创新点是，发现并阐明了弹性应力场作用下空位与晶界交互作用的基本物理过程：在张应力作用下，晶界会吸收空位，引起溶质非平衡晶界偏聚；压应力作用下，晶界会发射空位，引起非平衡晶界贫化。建立了描述此物理过程的晶界区力学平衡的结构方程和成分方程；？建立了张应力引起的非平衡晶界偏聚动力学方程？；用晶界区力学平衡的结构方程和成分方程？，首次通过实验测量计算出多晶材料晶界区的弹性模量；通过建立的动力学方程模拟实验结果，首次获得溶质原子－空位形成的复合体的扩散系数。

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。

Based on varying process of generator terminal parameters after excitation fault, shortages of excitation protective principle of static stability boundary and asynchronous impedance boundary are analyzed. It proposed that excitation fault research relates to large-disturbance stability. Because dynamic power-angle character of generator after excitation fault is non-sinusoidal, there are differences between dynamic power-angle character and static state power-angle character. So it isn't ideal to protective operation result based on small-disturbance stability and static stability boundary criterion. At the same time, it proposed that asynchronous boundary impedance criterion is a constant reactive power circle moving adown j Xd′. It can ensure complete loss-of-excitation generator measuring impedance enter into the circle, but can't ensure the other condition measuring impedance including impossible losing synchronism enter. So loss-of-excitation protection would be maloperation when system voltage drops short and recovers or generator rejects load.③Based on stability principle, it puts forward setting conditions and calculation method of generator loss-of-excitation protection by direct measuring power-angle.

以励磁故障后发电机端的相关参数的变化为基础，通过对以静稳定边界和异步阻抗边界作判据的两类三种现行励磁保护在原理上存在的缺陷分析，发现：励磁故障是一个大干扰稳定性问题，励磁故障后的发电机的动态功角特性与静态功角特性有很大的差异，已远非正弦曲线，因此基于小干扰稳定性原理、以静稳定边界作判据的保护必然动作不理想；异步边界阻抗判据是一个下移j Xd′的等无功阻抗圆，它可以保证完全失磁后的发电机测量阻抗能进入该阻抗圆，但不能保证完全失磁之外的其它状态不会进入该阻抗圆，因此在系统电压短时下降或发电机突然甩负荷等情况下可能启动该保护使之误动。

The results show that the absorbing effect of low-order Higdon absorbing boundary condition is undesirable and relatively strong boundary reflection exists in wave field snapshot and analog recording; the effect of traditional and improved PML absorbing boundary conditions are similar, which can effectively absorb and attenuate the boundary reflections from any angle.

结果表明，低阶Higdon吸收边界条件吸收效果较差，在波场快照和模拟记录中存在较强的边界反射；改进的PML吸收边界条件与传统的PML吸收边界条件效果相当，均能有效地吸收衰减任意角度的边界反射波。

Taking electrostatic field as an example problem, based on the general analytical series solution of electrostatic field,(1) the zero, first and second order asymptotic boundary conditions on circular truncation boundary; and (2) the zero and first order asymptotic boundary conditions on arbitrary polygonal truncation boundary are derived.

有限元法计算无界电磁场问题是电磁场数值分析中的一个重要课题，在这里计算精度与计算量之间的矛盾尤为突出。

Based on the boundary integral formula and natural boundary integral equation for the boundary value problems of biharmonic equation , the non-symmetrical banding solutions to the circular plate under thermal boundary conditions are gained by the Fourier series and convolution formulae.

根据双调和方程边值问题的边界积分公式和自然边界积分方程，利用傅立叶级数及卷积的几个公式，求得了相应变温边界条件下非对称载荷圆板的弯曲解，从实践上证明了此方法的可行性。

We have also presented the ω-circulant boundary condition and compared it with the helix boundary condition. Furthermore, we can also get another new boundary condition: the mixed boundary condition.

由此我们提出了ω循环型边界条件并将其与普通循环型及螺旋型边界条件作了分析和比较；进一步地，得到了一种新的边界条件：混合型边界条件。

In view of geological records preserved from different regions of the world are not identical, it's suggested that, when correlating the Ordovician-Silurian boundary, at the global boundary stratotype section, the FAD of N. persculptus be selected as the biomark, the transgression event identical to the FAD of N. persculptus as the auxiliary physical mark and the mass extinction and chemical anomaly events respectively as the auxiliary biomark and chemomark. In some regions with few graptolite, the Ordovician-Silurian boundary should be indicated by the auxiliary marks, such as the transgression event, mass extinction or chemical anomaly event, with the other fossil such as conodont nearest to other geological events as the provincial biomark for correlation. In other regions with much stratigraphic hiatus originated from the regression, the Ordovician-Silurian boundary should be marked by the regression-transgression event nearly relevant to the N. persculptus Zone.

鉴于不同地区留下的地质记录不完全相同，奥陶/志留系界线对比方法不同：在界线层型剖面上，以N.persculptus的首现为生物标志，以与之基本一致的海侵事件为辅助的物理标志，以生物集群绝灭事件和化学异常事件为辅助的生物和化学标志；在笔石极不发育的地区，则以海侵事件、生物绝灭事件或化学异常事件为辅助标志，以与其相距最近、并且具有区域对比性的其它门类化石作为界线对比的生物标志；对于由于海退事件所造成地层缺失很多的地区，则以海退/海侵事件作为划分界线的物理标志，并以相映的海侵事件的开始作为奥陶/志留系的分界。

Two problems were solved in numerical calculation, one was that a term of 1/r in Maxwell was divergence in cylindrical center where r=0, another was that the value of optical field at cylindrical center was difficult to decided when the cylindrical center set as a boundary condition in Maxwell equation, So the values of optical field need just calculate from cylindrical center to cylindrical boundary, comparing from cylindrical boundary to cylindrical boundary, near upon half CPU time and RAM saved.

计算中解决了在圆柱中心线上Maxwell方程存在发散项1/r以及用圆柱中心线作为边界条件时，中心线上光场值难确定的问题，因而光场只需从圆柱中心计算到圆柱边界，和以圆柱的两条边做为边界条件比较，节省了将近一半的计算时间和计算机存储空间。

The French are not suggesting a new EU treaty, but they have plenty of other wheezes.

法国人并不是在建议签署一个新的欧盟条约，但他们有许多其他的阴谋。

This letter was written by my brother.

这封信是我弟弟写的。