查询词典 approximation method

The finite-difference method of calculation on primary wave traveltime based on any rectangular grid and a local plane wavefront approximation has high precision and can apply to complex media with violent velocity variation.

基于任意矩形网格和局部平面波前近似的有限差分初至波走时计算方法精度较高并适用于强纵横向变速的复杂介质。

For the raft, an isoparametric element method and VoigtKelvin model are adopted, which can be used to derive viscoelastic element stiffness matrices, a reform of successive approximation of Rayleigh Quotient is used to solve the eigenvalue problem of the composite structure.

对于筏架结构，采用Voiget-Kelvin模型及等参元法，推导了约束阻尼层单元的刚度阵及将Rayleigh商的迭代步骤加以改进的方法来进行特征分析；对于艇体结构与声学介质耦合部分，采用艇体结构的"干"模态作坐标变换。

In order to overcome this problem, in this paper, the surface electric current of the conducting sea surface and the first-order scattering from the conducting plate are obtained by employing Physic Optics method. The backscattering field of the time-dependant sea surface is calculated by using Kirchhoff Approximation. Meanwhile, taking the advantage of a newly developed technique that utilizes the reciprocity theorem, the difficulty in formulating the secondary scattered fields from the composite target is reduced. The dependences of the backscattered field on the parameters, such as the wind speed and the sizes of the plate are discussed.

为了克服这一问题，本文应用物理光学近似求解了导体海面表面电流及导体平板的一阶散射场，应用基尔霍夫近似给出了海面的后向散射场，同时借助互易性定理降低了求解平板和海面之间二次耦合散射场的难度，讨论了平板尺寸、风速等对后向复合散射场的影响。

Based on the above results, the problems of the electromagnetic interaction between a perfect conducting plate and 1-D/2-D conducting slightly random rough surface and the problems of the electromagnetic interaction between a dielectric spherical particle and dielectric slightly random rough surface are investigated. By using the reciprocity theorem, Small Perturbation Method and Physical Optics approximation, the solution for the composite scattering field from the composite target is derived and evaluated, and the numerical results are discussed and analyzed.

在此基础上，用互易性原理分别研究了一维、二维导体微粗糙面与其上方金属导体平板目标的复合电磁散射及介质粗糙面与其上方球形粒子的复合电磁散射，结合互易性原理和粗糙面散射微扰法及物理光学近似导出了复合散射场的计算公式并进行了数值计算，对计算结果进行了讨论和分析。

First introduced the lattice-value information systems knowledge, and to partial order for the basis has been a new relationship: advantage, given the reduction and the core, the concept of simplifying the classification of features, it is also given on the approximation, and the approximate reduction of matrix determined theorem and the concept of identification, the final adoption of specific reduction of examples to illustrate this method is effective.

首先介绍了格值信息系统的相关知识，并以偏序关系为基础得到了一种新的关系：优势关系，给出了约简和核心，简化了概念的分类特征，也给出了上近似、下近似及约简的判定定理和辨识矩阵的概念，最后通过具体的例子说明这种约简方法是有效的。

Selection of response surface method with highly accurate and efficient approximation is greatly important in its application.

工程应用中选用拟合精度和拟合效率较高的响应面建模方法是其应用的关键。

They. separate the G matrix into a barenucleon-nucleon interaction V and correction term △ G. The projection method isonly applied to the correlation term △ G; which is parameterized by fourpseudo-mesons. Then the nucleon self-energy in the DBHF can be calculated with theG matrix in the relativistic Hartree-Fock approximation.

研究表明，我们利用G矩阵新的分解方法计算得出的不对称核物质自能，特别是中子物质标量自能、有效质量的结果与简单方法有很大的差别，如有效质量相差200MeV左右。

Impsons Integration: In numerical analysis, Simpson s rule is a method for numerical integration, the numerical approximation of definite integrals.

pecifically：：辛普森整合：数值分析中，辛普森法则是一种方法，数值积分，数值逼近定积分。具体来说

Using the elasticity and the singular integral equation method,an analysis of a pure bending beam containing a rigid linear inclusion is carried out under the Saint-Venant s approximation.

使用弹性力学和奇异积分方程方法，在Saint-Venant近似的精度下，对带有刚性线夹杂的纯弯曲直梁作了分析，求得了夹杂两侧的干扰界面应力及夹杂端点的应力强度因子，结果对带夹杂零件的强度设计有参考价值。

Its discretization is based on spectral elements in space and central differences method in time. The numerical result, shows that this approximation has spectral accuracy in space and up to second-order in time.

该解法引入一阶Clayton-Engquist-Majda吸收边界条件，在空间上利用谱元方法，在时间上利用中心差分的积分方法得到波动方程的离散形式，并给出具体算例进行了验证。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。