grating

DFT进行频谱分析时的三种现象 1、混叠：对连续信号采样，要求连续信号是带限的，采样频率要足够高。Fs应满足Nyquist采样定理才不产生混叠。 采样前加低通滤波器防混叠 2、频谱泄漏：DFT对时域信号进行了截断（相当于采样信号乘了一个窗函数），时域的乘积相当于频域卷积，改变了原信号频谱。 改用其他窗函数（非矩形）改善泄漏。 3、栅栏现象：DFT 只给出了频谱在采样点上的取值，采样点间的频谱内容丢失。(DFT spectrum analysis of a three phenomena, aliasing : continuous signal sampling, requiring continuous signal is band-limited, the sampling frequency should be high enough. Fs meet the Nyquist Sampling Theorem would not have aliasing. Sampling former low-pass filter plus anti-aliasing 2, spectrum leakage : DFT right time domain signal a disconnect (equivalent to a sampling signal by a window function). time domain is equivalent to the product of frequency-domain convolution, changes in the spectrum of the original signal. Window functions to switch to other (non-rectangular) to improve leakage. 3, fenced phenomenon : DFT spectrum is given only at the sampling point value, sampling points of the spectrum as lost.)

计算任意时域信号的非线性超声系数GUI，原创程序，学习GUI和非线性超声的一个参考例程，欢迎指教(Nonlinear ultrasonic coefficient GUI, any original program to calculate the time-domain signal, and nonlinear ultrasound study GUI a reference routines, welcome to enlighten)

用MATLAB做的解方程的程序源程序及演示课件。(do with MATLAB solution to the equation and demonstrate procedures source courseware.)

create feature for combination feature

一个不错的关于SVM的例程，大家可以下载下来做一个参考，个人认为很不错的(A good SVM program,I think it is a good reference.)

This program lets you put one image into the same voxel space as another image. E.g. you might want to extract a Brodmann area from the brodmann.img file that comes with MRIcro, and then put that set of 1x1x1mm voxels into the same voxel space as your functional data, which probably covers a smaller volume and has larger voxels. Then you can use the Brodmann area as an ROI to explore your functional results.

使用MATLAB程序自动生成六边形拓扑结构(MATLAB program automatically generate hexagonal topology)

ASK、PSK和FSK信号的盲识别仿真，仿真产生各类信号，分别可进行大类间的识别和类内识别，统计识别准确率。(Blind Identification ASK, PSK and FSK signal,simulation produces all kinds of signals, and can be identified in the identification between class categories, statistical recognition accuracy.)

说明：  多载荷多工况的结构拓扑优化代码，matlab实现(Structural Topology Optimization Code for Multi-load and Multi-working Conditions)

此源码是基于matlab编写的关于查找图像中图形的个数，及查找每个图形的重心并显示。(This source code is written in matlab based on the number of graphic image search, and find the center of each graph and display.)