以x(1)(n)为初始条件的GM模型

自1982年灰色系统理论创立以来,关于GM模型的研究,都是以序列X(1)的第一个分量作为灰色微分模型的初始条件进行建模的,这样造成对新信息利用不够充分。根据灰色系统理论的新信息优先原理,在建模过程中赋予新信息较大的权重可以提高灰色建模的功效。因此本文在建立灰色模型时,把X(1)的第n个分量作为灰色微分模型的初始条件,对GM模型进行了改进,从而使所建模型的预测精度大为提高。最后,通过实例验证了所建模型的实用性与可靠性。     

一类基于KTC的主动节点密钥建立协议

主动网络是一种功能强大、配置灵活的新型网络体系。该文介绍了主动网络技术以及密钥建立协议在主动网中的应用功能,论述了网络安全中的密钥管理以及伪随机密钥与初始向量的产生过程,给出了一个基于密钥传递中心的主动节点密钥建立协议。     

Initializing EM using the properties of its trajectories in Gaussian mixtures

A strategy is proposed to initialize the EM algorithm in the multivariate Gaussian mixture context. It consists in randomly drawing, with a low computational cost in many situations, initial mixture parameters in an appropriate space including all possible EM trajectories. This space is simply defined by two relations between the two first empirical moments and the mixture parameters satisfied by any EM iteration. An experimental study on simulated and real data sets clearly shows that this strategy outperforms classical methods, since it has the nice property to widely explore local maxima of the likelihood function.