下一代网络入侵防御研究

随着信息化的发展和网络应用的普及,针对企业和个人的各种攻击越来越复杂,攻击技术和策略也在不断调整,传统的入侵防御系统必须进化到能够处理先进的有针对性的威胁。首先介绍了下一代网络入侵防御系统的概念和主要功能,接着分析了和其它网络安全产品的关系,然后,阐述了下一代网络入侵防御典型产品的关键技术,最后,指出了下一代网络入侵防御的发展前景。     

IDS与IPS

IDS和IPS在网络安全保护方面各有利弊,通过分析两者的优势和缺陷,发现IDS主要适用于对来自网络的威胁的检测预防,而IPS技术在IDS的功能上增加了响应和主动防御功能。因此,在当前网络防御技术发展不太成熟的时候,需将IPS、防火墙、IDS等网络安全技术相结合在一起使用,才能有效的保证网络安全。     

新一代安全防御技术-IPS的研究

IPS是一种既能发现入侵行为、又能阻止入侵行为的新一代安全防御技术。本文先分析了IPS的工作原理及体系结构,然后对IPS进行分类,并将IPS与IDS进行了比较,最后介绍了IPS的特征。     

Ultrasonic weld properties of heterogeneous polymers: Polylactide and poly (methyl methacrylate)

This paper aims to investigate the effects of welding conditions and the correlation between welding strengths and interfaces structures on the weld between polylactide (PLA) and poly (methyl methacrylate) (PMMA). Using our proposed ultrasonic weld (USW) method, PLA and PMMA composites (PLA/PMMA) are valid to employ as interposed sheet (IPS) experimentally. There are optimum welding times and welding presses depending on the peak welding strengths. The maximum welding strength can reach as high as 90% of the tensile strength of the matrix PLA, while the welding time is 4 s and welding press is 0.6 MPa. But excessive welding presses are deleterious to the weld, and it can also bring IPS destroying during the weld work.     

INS/SFGPS PPP紧组合系统动态补偿滤波算法

惯性/卫星组合导航系统结合精密单点定位技术可有效提高导航定位精度。但精密单点定位技术一般需采用双频接收机,成本较高;同时该系统中采用载波相位作为部分或全部观测量,极容易受到周跳的影响而导致精度下降和系统不稳定。针对上述问题,设计了一种惯性/卫星精密定位紧组合导航系统以及基于动态周跳补偿的鲁棒滤波算法。该系统采用低成本的单频接收机(SFGPS),以精密单点定位技术(PPP)处理过的伪距和载波相位作为观测信息,与惯性导航系统(INS)等效观测量进行紧组合,建立了相应紧组合观测模型并引入周跳作为信息融合滤波状态模型中的状态量,以滤波器信息构建周跳检测统计量并对周跳幅值进行识别和估计,实时补偿观测量以提高观测信息精度,同时以前述周跳估计的结果对状态模型中周跳状态量部分滤波参数进行实时调节。上述方法通过动态补偿周跳误差提高导航精度,通过滤波器参数自适应调节提高滤波稳定性。仿真结果验证了该系统模型及算法的有效性。     

基于Snort的IPS模型

本文从现有安全防护产品的不足出发,简单分析入侵防御系统IPS的工作原理和发展趋势,以Linux防火墙Netfilter和开源入侵检测系统Snort相结合的方式建立了入侵防御模型,并采用改进了Snort的模式匹配算法,以提高检测效率。     

基于隐式梯形–时步保持法的3/12相电机建模

综合电力系统（integrated power system,IPS）包含3/12相双绕组发电机等特殊高阶非线性元件,现有电力系统电磁暂态仿真软件均不提供其仿真模型。为此,采用隐式梯形法对双绕组发电机数学模型进行差分离散化处理,通过定、转子分离迭代,推导出电机等效电路模型,并在PSCAD中建立双绕组发电机仿真模型。应用时步保持算法,将模型的仿真时步划分为计算时步和保持时步,提高了计算速度。最后,构建综合电力推进系统试验平台,发电机空载短路、推进系统调速的试验与仿真结果吻合,验证了建模方法的有效性和所建模型的正确性。研究表明,基于隐式梯形–时步保持算法的建模方法能够准确高效地建立双绕组发电机的仿真模型,可应用于EMTP类仿真软件,并可推广至IPS各类多相电机建模。     

Prediction tests by using ISF method for the geomagnetic disturbances

A so-called ISF method for predicting geomagnetic disturbances caused by solar wind storm blowing to the earth is suggested. The method is based on a combined approach to solar activity, interplanetary scintillation (IPS) and geomagnetic disturbance observations in 1966-1982, dynamics of disturbance propagation and fuzzy mathematics. Prediction test has been made for 24 large geomagnetic disturbance events that produced space disasters during the period of 1980 -1998, with the three-dimensional propagation characteristics, the best close degree of each radio source and the influence of the south-north components of interplanetary magnetic fields considered. The main results are (i) for onset time of the geomagnetic disturbance, events with relative error △Tpred/Tobs≤10% between the observation Tobs and the prediction Tpred, account for 45.8% of all events, ≤30% for 78.3% and >30% for only 21.7%; (ii) as for the magnetic disturbance magnitude, events with relative error ΔΣKp,pred/ΣKp,obs≤10% betwee     

Moving‐image‐sticking phenomenon induced by an outside force in liquid‐crystal displays

Abstract— Image deformation caused by an outside force is observed to remain for hours at high gray levels for liquid‐crystal displays (LCDs) in the multi‐domain (MD) vertical‐alignment (VA) mode. This so‐called moving‐image‐sticking phenomenon demonstrated a non‐symmetric luminance profile for the left and right viewing direction for MDVA‐mode LCDs which have original symmetric viewing‐angle characteristics. The generation of a stable reverse‐tilt domain by an outside force was assumed to be the cause of this phenomenon, and the stability of a reverse‐tilt domain under an electric fringe field was calculated by changing the electric‐fringe‐field distribution which determines the LC tilt direction. The domain of a given tilt direction is calculated to change to other tilt direction induced by a fringe field at a low gray condition, but to remain unchanged at a high gray condition. This agrees with the observed trends of duration time of the moving‐image‐sticking phenomenon.     

浅析IDS及IPS网络安全深层防护策略

随着网络入侵事件的不断增加和黑客攻击水平的不断提高,传统的防火墙或入侵检测技术(IDS)已显得力不从心,这就需要引入一种全新的技术-入侵防护(IntrusionPreventionSystem,IPS)。本文在分析IDS不足的基础上,探讨了IPS的工作原理和技术特征及其面临的挑战。并探讨了未来网络安全深层防护的策略。