查询词典 difference equation

Based on the diffusive equation of incoherent-feedback random lasers,whose gain is modified by adding a saturation factor,the evolution of the emitted light intensity in two-photon pumping random lasers varying with time is studied by use of finite difference method.

引言从20世纪90年代开始，人们对光在增益无序介质中与介质相互作用而产生的受激辐射现象的研究表现出了极大的兴趣[1—11]。实验上，国内外的学者们在不同的随机介质中观测到了光的放大。

A seven-node difference scheme of the diffusion equation was proposed to study the behaviors of transient electromagnetic field in complicated 3-D geoelectric body. Models of roadway and anomaly body were set up for simulating the transient field excited by a vertical magnetic dipole source. The result of numerical simulation shows that the presence of low resistive conductor leads to noticeable distortion of isolines for the "smoke ring" field, whereas the distortion is not so obvious where the roadway and the poor conductor are located.

为了探讨复杂三维地电体中瞬变电磁场的响应特征，推导了三维扩散方程的七点差分格式，建立了巷道和异常体模型，并对垂直磁偶源激发的瞬变场进行了数值模拟，观察到早期&烟圈&场在低阻体处等值线发生的明显畸变，在巷道和高阻体处的畸变较弱，随着时间的增加异常体的影响逐渐减弱。

After the deduction of high order temporal and special difference approximation to the wave equation, the snapshots of wave propagation in an infinite monoclinic media and synthetic three components surface and VSP data for a flat layered model are presented.

推导了交错网格中时间和空间上的高阶差分近似公式，并针对二维单斜各向异性介质，给出了具体的空间差分网格的形式。在上述理论的基础上，利用交错网格高阶有限差分技术，首次对单斜各向异性介质中波的传播特性进行了模拟。

In this paper, the finite-difference time-domain formation of Maxwell's equation is deduced and coded in perfectly matched layer in three-dimension cylindrical complex coordinates.

在三维柱坐系下推导了完全匹配层吸收边界条件的时域有限差分表达式，从而把 FDTD方法推广到完全三维柱坐标系中。

The results show that:(1) MnO2 deposition on the surface is the main factor resulting in cathode polarization, and the flowing of the solution can remarkably reduce this polarization. Furthermore, the buffered solution can reduce the polarization resulting from H+ concentration difference;(2) it is deduced from the polarization curve that the key factor influencing the performance of MFC is microbial number and metabolic rate and the electron transferring rate from microbial to electrode;(3) the power density arrives at the biggest, 824 mW/m2, when outer resistance is 300 Ω, which is accordance to the inner resistance,(284±18)Ω, deduced from I-V curve;(4) the influences of pH and permanganate concentration on cathode potential is in agreement to Nernst equation.

研究结果显示：(1) MnO2在碳纸表面的沉积是阴极极化的主要原因，而溶液流动可以明显降低极化程度；将高锰酸钾溶解在缓冲溶液中可以进一步降低阴极H+浓差极化；(2)根据极化曲线可以推断，影响电池输出功率的决定性因素应是微生物代谢反应速度和微生物与电极之间的电子传递速率；(3)随外电阻的变化，电池输出功率出现极大值824 mW/m2，相应外电阻为300 Ω左右，这与通过 I-V 关系曲线推导得到的电池内阻(284±18)Ω相吻合；(4) pH值和高锰酸钾浓度对电池阴极电极电势的影响符合Nernst方程。

Methods: Five patients with parkinsonism or dystonia were assigned to general anesthesia using an modified endotracheal tube.

本实验依照人体实验之相关规定进行，五位患有帕金森氏症或肌张力异常的病人接受神经立体定位手术。

If you can benefit from this book, it is our honour.

如果您能从本书获益，这将是我们的荣幸。