CFD-notes

针对多径效应的影响，提出了一种基于矩阵束的MIMO 雷达低仰角快速估计方法。该方法同时考虑了发射多径信号和接收多径信号，采用单样本数信号矢量构造了一个前后向矩阵束，并利用两个酉矩阵对该矩阵束进行降维处理，最后采用广义特征值分解的总体最小二乘法来估计目标角度。算法不需要估计数据协方差矩阵，可在低 信噪比和单样本数情况下，有效地克服多径效应，实现同时多目标低仰角估计，相比最大似然算法，避免了谱峰搜索，计算量小。仿真结果验证了该算法的有效性。(To overcome the multipath effect, a fast algorithm for low elevation estimation for MIMO radar via matrix pencil is proposed. The signals both in transmit multipath and receive multipath are considered. Firstly, a forward-backward matrix pencil is formed based on the single-sampled vector. Secondly, the reduced-dimensional processing is applied to the matrix pencil via two unitary matrices. Finally, the generalized eigen-decomposition is employed to estimate the low elevation in multipath environments directly. Without the covariance matrix estimation, the proposed method can overcome multipath effect effectively in case of low SNR and estimate multi-target simultaneously. Compared with Maximum Likelihood (ML) method, it avoids spectrum peak searching and reduces the computational burden. Numerical results verify the effectiveness of this method)

说明：  适合初学者学习的fluent网格划分以及udf动网格(A fluent udf example)

计算多材料单元平均应力应变,用于提取计算等效弹性模量 泊松系数(Calculate the average stress-strain of multi-material elements)

说明：  abaqus子程序学习资料，欢迎大家下载学习，共同讨论~(ABAQUS subroutine learning materials)

学习如何设置UPML吸收边界的3-D FDTD程序.对于初学者很有帮助(Learn how to set up UPML absorbing boundary of the 3-D FDTD procedure. Very helpful for beginners)

分维反映了复杂形体占有空间的有效性，它是复杂形体不规则性的量度。它与动力系统的混沌理论交叉结合，相辅相成。它承认世界的局部可能在一定条件下或过程中，在某一方面（形态，结构，信息，功能，时间，能量等）表现出与整体的相似性，它承认空间维数的变化既可以是离散的也可以是连续的，进而拓展了视野。(Fractal dimension reflects the validity of space occupied by complex bodies, which is a measure of irregularity of complex bodies. It combines with chaos theory of dynamic system and complements each other. It recognizes that the part of the world may be similar to the whole in certain conditions or processes (form, structure, information, function, time, energy, etc.). It recognizes that the change of spatial dimension can be discrete or continuous, thus expanding the horizon.)

无功功率补偿SVG，已经调试好了，可以用的(Reactive power compensation SVG, has been debugged, can be used.)

求矩阵奇异分解svd算法，共计4种实现方式，(for SVD matrix decomposition algorithm, for a total of four kinds of achievement,)

1、根据所给的中国版图数据 绘制显示基于北京54坐标系的经纬度数据 编写兰勃特投影转换程序，转换上述数据，并显示 编写墨卡托投影转换程序，转换上述数据，并显示 同时，要绘制相对应的经纬网格，网格间距5度 2、根据所给的世界版图数据 绘制显示基于WGS84坐标系的经纬度数据 编写墨卡托投影转换程序，转换上述数据，并显示 计算北京(116.4，39.8)到巴黎(2.2, 48.52)的大圆轨迹，并显示 同时，要绘制相对应的经纬网格，网格间距5度(1, according to the Chinese territory given display data drawn based on latitude and longitude data write Beijing 54 coordinate system Lambert projection conversion process, the conversion of the data, and displays the write Mercator projection conversion process, the conversion of the data, and display the same time, Draw the corresponding latitude and longitude grid, the grid spacing of 5 degrees 2, according to the world map rendering display data written to the Mercator projection based on latitude and longitude data conversion program WGS84 coordinate system, the conversion of the data, and displays the calculation Beijing (116.4, 39.8) to Paris (2.2, 48.52) the great circle track and display the same time, to draw the corresponding latitude and longitude grid, the grid spacing of 5 degrees)

最小二乘法寻找最佳函数匹配，用以数值计算，优化曲线(The least square method is used to find the best function matching for numerical calculation and curve optimization.)