基于数据挖掘的Snort系统改进模型

针对Snort系统对新的入侵行为无能为力的缺点,设计了一种基于数据挖掘理论的Snort网络入侵检测系统的改进模型。该模型在Snort入侵检测系统的基础上增加了正常行为模式挖掘模块、异常检测引擎模块和新规则生成模块,使得系统具有从新的入侵行为中学习新规则和从正常数据中学习正常行为模式的双重能力。实验结果表明,新模型不仅能够有效地检测到新的入侵行为,降低了Snort系统的漏报率,而且提高了系统的检测效率。     

一种基于组移动性的战术Ad Hoc网络分群算法

如何合理地保障分群是战术Ad Hoc网络实现分层网络并进行分群路由的前提和核心环节。针对这个核心问题,引入组移动特征,结合本地移动性参数和节点的能量,面向战术Ad Hoc网络,提出了一种基于组移动性的分群算法,并仿真分析了该算法的分群性能。     

轮腿式机器人倾覆稳定性分析与控制

对于运动在不平坦地形中的移动机器人而言,其倾覆稳定性非常关键．设计了一种结构对称的轮腿式机器人,它有4个独立的轮腿运动单元,能够变化多种构形．采用动态能量稳定锥方法和倾覆稳定性指数对机器人的稳定性进行综合评价,建立了一个模糊神经网络自适应控制系统．根据稳定性指数值,该系统可以实时改变机器人的构形和速度,保证其倾覆稳定性．正弦路面上的仿真结果表明,该系统所产生的动作实时性好、可靠性高,能够降低机器人自主越障过程中的危险．     

基于横摆角速度的汽车ABS控制策略的研究

研究汽车制动系统中,为了保证缩短制动距离的同时,改善汽车在附着系数分离的非对称路面上行驶制动的方向稳定性,结合单轮独立控制与低选控制方式,以横摆角速度为控制参数,提出一种兼顾制动距离和方向稳定性的ABS整车控制策略:ABS混合控制策略.建立汽车制动相关模型,对4种控制方式进行仿真分析.比较4种不同控制策略的仿真结果,表明以横摆角速度为控制参数的ABS混合控制策略能在制动距离与制动方向稳定性中找到合理的平衡点,既能充分利用每 个车轮的路面附着系数,又能防止汽车在非对称路面行驶时产生较大的制动跑偏量,提高汽车制动时的方向稳定性.综合考虑制动距离和制动方向稳定性两项指标,以横摆角速度为控制参数的ABS混合控制方式制动效果最优.     

含离散和分布时变时延神经网络系统的指数稳定性

针对一类含有离散和分布时延神经网络,在神经激活函数较弱的约束条件下,通过定义一个更具一般性的Lyapunov泛函,使用凸组合技术,得到了新的基于线性矩阵不等式表示的指数稳定性判据.与现有结果相比,这些判据具有较小的保守性.仿真算例表明,得到的结果是有效的且保守性小.     

二级倒立摆的Sugeno型模糊神经网络控制

为了提高二级倒立摆系统实时控制的响应速度和稳定性,在设计Mamdani型模糊推理规则控制器控制倒立摆系统稳定的基础上,设计了一种更有效率的基于Sugeno型模糊推理规则的模糊神经网络控制器.该控制器使用BP神经网络和最小二乘法的混合算法进行参数训练.能够准确归纳输入输出量的模糊隶属度函数和模糊逻辑规则.通过与Mamdani型控制器的仿真对比及实际控制实验结果,表明该Sugeno型模糊神经网络控制器时二级倒立摆实验装置的控制具有良好的稳定性、快速性和较高的控制精度.     

Switching contact task control in hydraulic actuators: Stability analysis and experimental evaluation

A switching contact task control for hydraulic actuators is proposed. The controller is built upon three individually designed control laws for three phases of motion: (1) position regulation in free space, (2) impact suppression and stable transition from free to constrained motion and (3) force regulation in sustained‐contact motion. The position and force control schemes are capable of asymptotic set‐point regulation in the presence of actuator friction and without the complexity of sliding mode or adaptive control techniques. The intermediate impact control scheme is included for the first time to dampen the undesirable impacts and dissipate the impact energy that could potentially drive the whole system unstable. The solution concept and the stability of the complete switching control system are analyzed rigorously using the Filippov's solution concept and the concept of Lyapunov exponents. Both computer simulations and experiments are carried out to demonstrate the efficacy of the designed switching control law. Copyright © 2009 John Wiley & Sons, Ltd.     

Stability of solutions of stochastic functional-differential equations with poisson switchings and entire prehistory

The Markov properties of the solutions of Ito-Skorokhod stochastic functional-differential equations (SFDEs) with entire prehistory are considered, the concept of a weak infinitesimal operator is introduced for a Markov process that is a solution of an SFDE, and the strong solution of the SFDE is analyzed for stability. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 123–134, January–February 2009.     

A piecewise analysis method to stability analysis of linear continuous/discrete systems with time‐varying delay

The delay‐dependent stability problem of linear continuous/discrete systems with time‐varying delay is investigated based on a piecewise analysis method (PAM). In the method, the variation interval of the time delay is firstly divided into several subintervals. By checking the variation of the Lyapunov functional in every subinterval, some new delay‐dependent stability criteria are derived. Several numerical examples show that our method can lead to much less conservative results than those in the existing references. Moreover, when the number of the divided subintervals increases, the corresponding criteria can provide an improvement on the results. Copyright © 2008 John Wiley & Sons, Ltd.     

Delay‐dependent stability and stabilization of neutral time‐delay systems

This paper is concerned with the problem of stability and stabilization of neutral time‐delay systems. A new delay‐dependent stability condition is derived in terms of linear matrix inequality by constructing a new Lyapunov functional and using some integral inequalities without introducing any free‐weighting matrices. On the basis of the obtained stability condition, a stabilizing method is also proposed. Using an iterative algorithm, the state feedback controller can be obtained. Numerical examples illustrate that the proposed methods are effective and lead to less conservative results. Copyright © 2008 John Wiley & Sons, Ltd.