Optimization of parabolic bars for maximum Bragg resonant reflection of long waves

This paper presents an analytical solution for the problem of the long wave reflection by a series of artificial bars with parabolic configuration in terms of the associated Legendre functions. It is shown that both the reflection and transmission coefficients depend solely upon the number of bars, the dimensionless bar height, the dimensionless bar width and the dimensionless bar distance. Particularly, under the Bragg resonance condition, i.e., the distance between two adjacent bars is about half of the wavelength of the normal incident waves, the analytical solution for the peak Bragg resonant reflection is obtained, which reveals that the peak Bragg resonance depends upon the number of bars, the dimensionless bar height and the dimensionless bar width. Based on this solution, the optimization of the parabolic bars is made to obtain the maximum Bragg resonance and a group of optimal curves, which may be very useful in the design of Bragg breakwaters with parabolic bars.     

一种新的差分进化算法

针对高维复杂函数的优化问题,提出了一种新的差分进化算法（NDE）。该算法在运行中根据迭代次数自动地调整交叉概率因子,从而在搜索的初始阶段提高种群多样性,而在搜索后期加强局部搜索能力。对几种经典函数的测试表明,新算法不仅具有很强的全局搜索能力,而且能有效避免早熟收敛问题。