入侵检测的1类支持向量机模型

计算机网络尤其是互联网的迅速发展与普及 ,使得信息安全已经成为一个全球瞩目的重要研究课题。随着攻击技术的不断进步与更新 ,迫切需要一种有效的入侵检测技术来保护信息系统的安全。由于几乎所有的攻击与滥用都被记录在系统的网络数据中 ,因而可以基于计算机系统的网络数据构造入侵检测系统。在对网络数据进行深刻的分析和研究的基础上 ,提出了入侵检测的 1类支持向量机模型。第一 ,构造适于异常点检测的1类支持向量机模型 ;第二利用抽象化的网络数据对该模型进行训练以确定其中各个参数的值。实验表明 ,该方法是行之有效的     

CRITICAL STATE OF SALT-WATER UPCONING BENEATH ARTESIAN DISCHARGE WELLS1

ABSTRACT: An approach, based on the realization of the vertical components of flow is presented to determine the free surface of gravity wells and the shape of salt-water upconing in artesian aquifers. The transitional stages from pumping fresh water to pumping salt water at the critical condition are discussed. Vertical hydraulic resistances, being determined and included in the flow domain, allow the use of the finite-difference approximation in a simple form. The suggested approach implies the use of either simple modeling or computing techniques.     

山东省地下水位下降引发的灾害及减灾对策

近二十年来山东省经济迅速发展与水资源匮乏的矛盾不断加剧。超量开采地下水导致地下水位持续的急剧下降，其结果引发了地裂缝、地面塌陷、海（咸）水入侵、生态环境恶化等一系列人为自然灾害。本文分析了这些灾害的基本特征并指出解决水资源不足是促进山东省经济持续高速发展并减轻地下水位下降灾害的根本措施。     

高速网络环境下的入侵检测

实现高速网络中实时入侵检测与预警已经成为目前网络安全所面临的问题。笔者首先分析了当前入侵检测系统中模式匹配算法 ,对模式匹配算法作了改进 ;接着对Rete算法进行了分析 ,并针对Rete算法的不足 ,在Rete网算法的基础上引入了FRete网算法 ,在此基础上建立了一种基于FRete匹配算法的推理机 ,对可疑事实进行推理 ;然后在此基础上设计了一种基于高速网络环境的入侵检测系统 ;最后建立了对入侵检测系统进行性能测试的仿真实验环境。通过上述的改进 ,提高了入侵检测系统的运行速度和效率 ,能较好地适应高速网络环境下的入侵检测。     

Food availability,intrusion pressure and territory size: an experimental study of Anna's hummingbirds (Calypte anna)

Theoretical considerations implicate food availability and intrusion pressure as important determinants of territory size, but empirical studies have led to contradictory conclusions about cause-and-effect relationships among these three variables. To investigate this problem, we provided patches of electronically controlled artificial flowers, which were defended by male Calypte anna. Food availability was experimentally manipulated, and intrusion rate and territory size were calculated from behavioral observations of the territory owner. Changes in both food availability and intrusion rate were found to be significantly correlated with changes in territory size under certain conditions. Intrusion rate, which was influenced by food availability, was negatively associated with territory size so long as food availability was high. This association persisted even after possible effects of food availability were controlled statistically. Food availability was negatively correlated with territory size only when intrusion rates were high and after owners had been defending territories for 3 days. As food availability and intrusion rate increased, owners increasingly restricted their defense to the patch itself; partial regressions revealed a significant association for intrusion rate but not food availability. When intrusion rate was low and food availability varied from low to high levels, no relationship was observed between food availability and territory size, apparently because of opposing influences of food abundance on territory size. Correspondence to: P.W. Ewald