查询词典 finite difference approximation

We investigate mainly solving the hyperbolic and parabolic equations by using the MQ quasi-interpolation. The underlying idea of our means is that: employing the derivative of the MQ quasi-interpolation to approximate the spatial derivative of the PDE, while the approach of the temporal derivative of the PDE is used a finite difference.

我们主要就MQ拟插值在双曲型方程和抛物型方程中的应用进行了研究，其基本思路是：利用MQ拟插值的导数逼近微分方程的空间导数，而微分方程的时间导数则采用有限差分逼近。

Then, an approximate formula for the buckling loads is established, which is simple and efficient by means of comparison with the results computed by finite difference.

与有限差分法得到的结果比较，本文推荐公式得到的结果是简便的，精确的。

We introduce the principle and arithmetic of Finite Difference Time Domain method particularly, and primarily discuss on several essential questions including excitation sources, the conditions of stability of calculation, and Perfectly Matched Layer boundary conditions. All of these factors have effect on the results of the numerical simulation.

2详细介绍了有限时域差分法(Finite Difference Time Domain， FDTD)的原理和算法，着重讨论和分析了激励源设置、FDTD法的稳定条件、PML吸收边界条件等几个关键问题，这些因素会直接影响模拟结果。

It then deduces the associated Euler-Lagrange equation and established the corresponding diffusion equation. Finally, a finite difference inpainting algorithm is proposed.

根据所建立的修补模型，利用变分原理推导出对应的Euler-Lagrange方程，建立了与之对应的扩散方程。

A differential difference type adaptive law and an adaptive iterative learning controller are constructed to ensure the asymptotic convergence of tracking errors in the sense of square error norm on the finite interval, by introducing a Lyapunov-like function, a sufficient condition of the convergence of the method is given.

通过引入微分－差分自适应学习律，设计了一种自适应控制策略，使得跟踪误差在一个有限区间上的积分渐近收敛于零；通过构造Lyapunov-like函数，给出了闭环系统收敛的一个充分条件。

Improvement of MT migration tomography technology Based on the immanent relationship between tomography purpose and suitable frequency segment selection, we raise an entire frequency segment multi-parameter tomography scheme of MT finite difference migration. We establish a mathematical relationship among apparent electromagnetism reflectance, migration reflectance, background resistivity and the true resistivity distribution. After the introduction of TE/TM mode superpose rate, we carry out the associated resistivity tomography of two polarization mode to adapt the practical data interpolating situation.

大地电磁偏移成像的改进：针对频段选择和成像效果的内在关系，提出全频段、多参数有限差分偏移的解决方案；构建视反射系数、偏移反射系数、背景电阻率与实际电阻率分布的数学关系实现偏移电阻率成像；同时引入TE、TM模式加权因子以实现两个模式的联合偏移电阻率成像，更好的适应解释工作需要。

While using three—points backward finite difference to imitate the radiation condition, we accept Raven's〓 idea to shift collocation points upstream a short distance.

在用三点向后差分格式模拟辐射条件时，接受了Raven〓的建议，将单元控制点向后移动了一段距离。

This thesis consists of two parts. The first one was that boundary value problem was discrete with five point difference method. Three kinds of memory formats were studied, which were full matrix, half band width and row compress sparse. Full matrix memory format and half band width memory format first was contrasted. The results show that half band width has efficiency in space. Then the algebraic system of finite element method was solved by Gauss-Seidel iteration method to popular row compress sparse memory format.

本论文由两部分组成，第1部分针对边值问题，用5点差分格式进行离散，并对离散矩阵这类大型稀疏矩阵，研究了系数矩阵的3种存储格式的优劣，即：满矩阵存储格式、半带宽存储格式和按行压缩稀疏存储格式，首先我们将满矩阵存储方式和半带宽存储格式进行了对比，迭代法的数值实验表明：利用半带宽存储的矩阵在空间运算方面具有高效性；然后针对目前数值实验中流行的按行压缩稀疏存储格式，实现了有限元离散代数系统的迭代法的求解。

To give the definition of the mass concrete and to concrete\'s cracks together with practical meanings of control ,and give a brief review on the research in the field at home and abroad, at last, methods to control temperature crack of the mass concrete from several aspects such as design measures,concrets material, construction schedules.etc are summed up; To explain the physical mechanics of the concrete and computing methods-Difference Method and Finite Element Method, and illustrate the application of their specific methods repectively;Several temperature factors that can influence the temperature stress of mass concrete baseplate are analyzed. The influence degree of temperature factor can be got through the ANSYS simulation computation the control of temperature can control the temperature stress, consequently control the temperature crack of mass concert baseplate; through the influence of the crack resistance ability of mass concrete baseplate which takes the reinforcement as a part is analyzed. By ANSYS simulation, the best suited volume ratio of reinforcement is found out, at same time the layout of reinforcement with the same volume ratio can also affect the resistance ability of mass concrete baseplate. Sum up of above analysis, anti-crack function of steel bar in early mass concrete baseplate is obvious, so it\'s necessary to consider beneficial effect of construction steel bar in research of temperature control on mass concrete baseplate.

本文先容了大体积混凝土及混凝土裂缝的基本概念，对国内外在这个领域里的研究现状作了扼要叙述，并从结构设计、混凝土材质、施工措施等方面总结了大体积混凝土温度裂缝控制的方法及防止措施；阐述了混凝土的基本物理力学性能，总结了大体积混凝土温度计算的方法——差分法和有限元法，并分别举例说明其具体应用的方法；分析了影响大体积混凝土底板温度应力的几种温度因素，利用ANSYS模拟计算，得出了每种因素的影响程度，通过分析提出了在这几种温度影响因素下如何通过控制温度以达到控制温度应力从而来控制裂缝的具体建议；针对大体积混凝土基础底板中配筋的不同对混凝土底板抗裂能力的影响不同，利用ANSYS进行模拟分析，得出底板中最合适的体积配筋率，同时分析了在相同体积配筋率下钢筋的具体布置对大体积混凝土基础底板抗裂能力的影响，分析表明，配置钢筋对混凝土结构的开裂阻止作用明显，在研究大体积混凝土温度裂缝题目时，要考虑钢筋在其中的有利作用。

The finite-difference time-domain method is adopted to simulate the propagation of the optical wave in the beam splitter.

采用时域有限差分法模拟了光波在分束器中的传播行为，并计算了分束器的传输效率。

We were cousins—his grandfather was King of Scots,and his great-grandfather was Henry VII of England.

我们是堂姐弟——他的祖父曾是苏格兰国王，他的曾祖父是英格兰的亨利二世。

I do want to help you, but I am in a quandary now!

我是想帮你，但是我现在左右为难啊！