基于循环反向编码的三维人脸测量方法

针对人脸测量时的抖动现象，设计了一种循环反向编码方法。该方法无需专门投影反向二值条纹辅助边缘点定位，减少了投影图案的数量。用循环的三帧条纹图像代替原本利用正反两帧条纹图像定位的方式，提高边缘点检测精度的同时能够有效消除定位偏差。实验表明，所提方法能够有效提高测量速度，同时保持较高的测量精度，减少点云中的运动波纹。     

Simulation Study on Dam Break Flow Based on the B-Spline Material Point Method北大核心CSCD

The dam break flow poses a common free surface flow problem in hydraulic engineering, and its ac⁃ curate simulation is of great engineering significance. The B⁃spline material point method (BSMPM), as an im⁃ proved algorithm of the material point method (MPM), has optimized accuracy and convergence in material point calculations and unique algorithmic advantages in free surface flow problems. Based on the BSMPM, a weakly compressible BSMPM (WC⁃BSMPM) was developed through introduction of an artificial equation of state. The simulation of the dam break flow problem was carried out, with the effects of the order of the B⁃ spline interpolation basis function on the simulation results analyzed. The results show that, the simulated fluid wavefront position, the wavefront velocity and the elevation variation at a given position are basically consistent with the existing experimental results. As the order of the basis function increases, the computation time will lengthen for about 1.5 times. However, the computation times of the BSMPM of different orders will uniformly increase approximately linearly with the background grid size. The validity of the WC⁃BSMPM simulation of the dam break flow problem was verified. The research provides a new idea and method for the simulation of dam break flow problems. © 2023 Editorial Office of Applied Mathematics and Mechanics. All rights reserved.     

蝴蝶定理在高考试题中的应用——2022全国甲卷理科第20题背景探幽

<正>1 试题呈现例 (2022全国甲卷520)设抛物线C:y2=2px(p>0)的焦点为F,点D(p,0),过点F的直线交C于M,N两点.当直线MD垂直于x轴时，|MF|=3.(1)求C的方程；(2)设直线MD,ND与C的另一个交点分别为A,B,