back-forward-power-flow

计算在不同湿度下，不同频率下，大气的衰减系数。(Calculation under different humidity, different frequencies, atmospheric attenuation coefficient.)

完成不带PML边界的2维声波介质波场正演(Forward modelling of the wave field in two-dimensional acoustic medium)

说明：  隐马尔可夫的经典文献，和通俗易懂的PPT，很好的经典资料，文献常被应用，甚至PPT都经常被模仿(Hidden Markov classic literature, and user-friendly PPT, classic good information, the literature is often applied, or even PPT are often imitate)

一种快速富式变换源程序,对于数字信号处理非常有用。(a usefull FFT code is very convenient to signal process )

在有限元分析中的网格划分好坏直接关系到模型计算的准确性，这里是关于网格划分的一些讨论。(In in the analysis of finite element mesh is directly related to the accuracy of the calculation model, there is some discussion about grid division.)

说明：  并联机器人MARALAND,其数值解及解析解，正解和逆解以及雅可比矩阵及动力学问题分析(Parallel robot maraland, its numerical solution and analytical solution, positive solution and inverse solution, Jacobian matrix and dynamics analysis)

有限元分析源代码，能分析梁单元、膜单元、壳体单元等常用的有限元单元，并能计算模态、振型等(Finite element analysis of source code, capable of analyzing beam element, membrane element, shell element, such as commonly used finite element module, and the calculation mode, vibration mode, etc.)

求解界约束问题的截断共轭梯度法，是最近刚出来的方法(The truncated conjugate gradient method for solving boundary constraints is a recent method.)

利用五点差分格式和Jacobi迭代法，求解精确解和数值解的误差，判断阶数是否正确(Five-point difference scheme and Jacobi iteration method are used to solve the error between exact solution and numerical solution and to judge whether the order is correct or not.)

利用FFT估计正弦信号的频率,要估计一个叠加了高斯白噪声的正弦信号 的频率 ，可以通过对x(n)做傅里叶变换，得到频谱图，找出幅度的最大值对应的频率值 ，进行多次变换，求出均方误差 。改变信噪比SNR，通过仿真可以得出随着信噪比增加，均方误差减小。(Sinusoidal signal using FFT frequency estimation, to estimate a Gaussian white noise superimposed on the frequency of sinusoidal signals, can be achieved by x (n) be the Fourier transform to get spectrum to identify the magnitude of the frequency value corresponding to the maximum , several transformations, find the mean square error. Change the signal to noise ratio SNR, the simulation can be drawn as the SNR increases, the mean square error decreases.)