gezhongchuang

DistMesh giving a singular FEM matrix?(Hi Anyone here with some experience of using DistMesh in finite element code? I m solving the scalar Helmoltz equation in an annular region in 2D: rho_1 < rho < rho_2 where rho_1 is the radius of a Perfect Electric Conducting cylinder and rho_2 is where the mesh is truncated using an Absorbing Boundary condition. Now, I ve written code to mesh the region myself (by dividing the region into annular rings and picking a fixed number of points on each ring) and I ve written another program which uses DistMesh to mesh the region. I get a nice solution using my own meshing code but the FEM matrix becomes singular when I use DistMesh. This is the DistMesh Code I used: Circle with hole rABC=1.5 rCyl=0.5 fdstring=sprintf( ddiff(dcircle(p,0,0, f),dcircle(p,0,0, f)) ,rABC,rCyl) fd=inline(fdstring, p ) box=[-2,-2 2,2] [p,N]=distmesh2d(fd,@huniform,0.04,box,[]) I tried changing box and the 0.04 value (initial edge length). But every time, the matrix becomes sin)

一种ESPRIT算法（教学实验，对初学者很有帮助）(a kind of ESPRIT , it may be helpful to the leaner of matlab and signal processing)

denoise In BayesShrink[5] we determine the threshold for each subband assuming a Generalized Gaussian Distribution(GGD) . The GGD is given by GG¾ X ¯ (x) = C(¾ X ¯ )exp¡ [® (¾ X ¯ )jxj]¯ (6) ¡ 1 < x < 1 ¯ > 0, where ® (¾ X ¯ ) = ¾ ¡ 1 X [ ¡ (3=¯ ) ¡ (1=¯ ) ]1=2 and C(¾ X ¯ ) = ¯ ¢ ® (¾ X ¯ ) 2¡ ( 1 ¯ ) and ¡ (t) = R1 0 e¡ uut¡ 1du. The parameter ¾ X is the standard deviation and ¯ is the shape parameter It has been observed[5] that with a shape parameter ¯ ranging from 0.5 to 1, we can describe the the distribution of coefficients in a subband for a large set of natural images.Assuming such a distribution for the wavelet coefficients, we empirically estimate ¯ and ¾ X for each subband and try to find the threshold T which minimizes the Bayesian Risk, i.e, the expected value of the mean square error.

DualThurst策略，经过改编，盈利能力较好(The DualThurst strategy has been adapted better profitability)

Matlab Voltag sag mitigation simulation file

调制解调器（即Modem），应用程序编程源码，很好的参考资料。(Modem (ie Modem), application programming source code, a good reference.)

主成分分析法，用于将低数据维度，减小有相关性的数据特征。(dimensionality reduction)

移动无线信道COS207模型MATLAB程序,对做信道仿真的朋友有参考价值(Mobile radio channel model MATLAB COS207 procedures, channel simulation of a friend doing a valuable reference)

s函数学习的入门资料，很详细的介绍s函数的写作方法(s function study of introductory information, very detailed)

There are 19 questions and 1 programming exercise. Some of them are very easy, some of them are really hard and challenging, and these will be marked as such. If you don’t want to be challenged too much, you can skip the hard questions