seagrid

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：  利用python进行因子分析,因子分析可以进行降维!(Using Python factor analysis, factor analysis can reduce dimensionality!)

从旋转矩阵到四元数的转换，matlab代码。(From the rotation matrix to quaternion conversion, matlab code.)

异或校验，用于北斗一代数据计算校验码，已验证(XOR checksum for the data checksum generation Beidou, Verified)

umat abaqus plasticity

将字符串合并的时候要注意中间的空格，否则可能在合并时出错。我调试了好久才发现(combine the string,essential to focus the length of string)

常微分方程求解的搜索延拓法，克服了Newton-Raphson法对初值问题影响过大的问题(Solving Ordinary Differential Equations search continuation method to overcome the Newton-Raphson method for initial value problem of the impact of the problem is too large)

应用于高速碰撞的相关子程序，考虑了在高速碰撞中单元畸变的沙漏模型。。(Related subroutines used in high-speed collision, taking into account distortion in high speed crash in the hourglass model unit. .)

说明：  matlab调用cplex12.1的例子，这些例子对matlab的cplex接口函数做了非常详细的说明，适用于cplex-matlab的初学者(matlab call cplex12.1 the examples that the cplex interface function of matlab to do a very detailed explanation for beginners cplex-matlab)

ABAQUS的二次开发，道路厚度与温度对路基的影响，来自廖公云老师的《ABAQUS有限元软件在道路工程中的应用》(ABAQUS secondary development, the road thickness and temperature of the roadbed, from Liao Gongyun teacher "ABAQUS finite element software in road works)