基于遗传操作的延迟和度约束的多播路由启发式算法

基于启发式思想的简单性和路径相似性原理，采用遗传算法的交叉和变异操作，提出了一种快速的满足延迟和度约束的最小费用多播路由树的生成算法(DDCMRA)，以解决直接修改延迟约束或者度约束多播路由算法时寻优时间长、并且可能导致部分目的节点因不能满足延迟或者度约束而不能加入多播的问题．仿真结果显示。该算法获得的多播路由树满足延迟和度约束，费用较少，运行时间接近CSPT和RA算法．该算法也为动态多播路由树生成和网络负载平衡提供了一种方法．     

Digital chaotic sequence generator based on coupled chaotic systems

Chaotic systems perform well as a new rich source of cryptography and pseudo-random coding. Unfortunately their digital dynamical properties would degrade due to the finite computing precision. Proposed in this paper is a modified digital chaotic sequence generator based on chaotic logistic systems with a coupling structure where one chaotic subsystem generates perturbation signals to disturb the control parameter of the other one. The numerical simulations show that the length of chaotic orbits, the output distribution of chaotic system, and the security of chaotic sequences have been greatly improved. Moreover the chaotic sequence period can be extended at least by one order of magnitude longer than that of the uncoupled logistic system and the difficulty in decrypting increases 2¹²⁸*2¹²⁸ times indicating that the dynamical degradation of digital chaos is effectively improved. A field programmable gate array (FPGA) implementation of an algorithm is given and the corresponding experiment shows that the output speed of the generated chaotic sequences can reach 571.4~Mbps indicating that the designed generator can be applied to the real-time video image encryption.