Numerical Simulation for Ventilated Supercavitation High Speed Underwater Vehicle

Supercavitation is a revolutionary technique to achieve high drag reduction for underwater vehicle. It can help us to break through the conventional speed barrier. This article presents a numerical algorithm for ventilated supercavitation flow field based on mixture multiphase flow model, briefs the calculation results and compares them with that tested in high-speed water tunnel and towing tank. The mathematical model, its numerical calculation method, computational region and boundary conditions are discussed in detail. Some pertinent nondimensional parameters about the ventilated supercavitation, such as geometrical configuration of supercavity, drag coefficient and ventilation rate are investigated. Reynolds number is selected to predict gas ventilation rate instead of Froude number. Finally, based on the test and simulation results, a semi-empirical formula of the ventilation rate estimation suitable for different conical angle caritators is proposed.     

广义微分中值定理

对于k阶可导函数,利用拉格朗日中值定理,证明了函数的k阶导数与函数值之间的关系;对于s阶可导函数(s>k),证明了函数的s-k阶导数值与函数的s阶导数之间的关系.给出了常见的k=2,k=3,k=4对应的定理及其证明.     

带诊断监视器的高速VCSEL驱动器MAX3740A

本文介绍了MAX3740A的主要性能、引脚功能、内部结构及工作原理，并结合典型应用电路，介绍了其应用设计过程。     

基于免疫遗传算法的图像阈值分割

基于最大熵准则的图像阈值分割算法是一个图像分割的最优化问题，算法的运算量很大，用一种基于免疫调节机制的免疫遗传算法求解该准则下图像的一组最佳分割阈值，不仅提高了运算速度，而且克服了一般遗传算法的不足，仿真实验证明了该算法对复杂图像的良好分割效果和较强的实时处理能力。