半混响环境中水下结构辐射声功率测量

本文参照空气声学的方法,在水池的半混响环境中,测量了两个相似加肋圆柱壳模型的水下辐射声功率,并利用声辐射的理论相似关系进行校验,在高频段测量偏差为1-2dB。     

Rotation-invariant texture analysis using Radon and Fourier transforms

Texture analysis is a basic issue in image processing and computer vision,and how to attain the rotation- invariant texture characterization is a key problem.This paper proposes a rotation-invariant texture analysis technique using Radon and Fourier transforms.This method uses Radon transform to convert rotation to translation,then utilizes Fourier transform and takes the moduli of the Fourier transform of these functions to make the translation invariant.A k-nearest-neighbor rule is employed to classify texture images.The proposed method is robust to additive white noise as a result of summing pixel values to generate projections in the Radon transform step.Experiment results show the feasibility of the proposed method and its robustness to additive white noise.