网络入侵检测系统中的漂移检测

目前基于机器学习的入侵检测系统大都建立在入侵数据始终保持统计平稳的假设之上,无法应对攻击者有意改变数据特性或新型攻击方式的出现,而导致的检测率下降的状况.对于上述问题,即攻击漂移,提出了加权Rényi距离的检测方法.在KDD Cup99数据集上的实验证明,Rényi距离可以有效地增强检测效果;在检测到漂移后,通过重新训练模型可以使得对攻击的识别率显著提高.     

有理二次Bézier形式共轭双曲线段的几何计算

考虑有理二次Bézier形式的相互共轭的双曲线的控制顶点之间的关系,给定表示一段双曲线的标准型有理二次Bézier曲线,目标是求出它的共轭双曲线上相应段的控制顶点。首先给出共轭双曲线段的自然定义;接着通过参数变换,将有理二次Bézier形式和一般参数形式进行转换,并把这种转换对应到矩阵,以给出所求控制顶点的显式表达;最后,给出表达式的几何意义,即共轭双曲线段的控制顶点可由原双曲线的控制顶点通过两次线性插值得到。     

一类双参数三次Bézier曲线的形状分析

为了分析清楚形状参数对一类双参数三次Bézier曲线形态的影响及实现其对该曲线形状的调控,利用包络理论与拓扑映射的方法对一类双参数三次Bézier曲线进行了形状分析,明确了形状参数对曲线的影响,画出了曲线的形状特征分布图,得出了曲线上有奇点、拐点和曲线为局部凸或全局凸的充分必要条件,这些条件完全由控制多边形的相对位置表示,并进一步讨论了形状参数对曲线形状的影响。     

基于Bézier曲线的两平行线间缓和曲线构造

利用五次 Bézier 曲线,构造了一条含形状参数的两平行线间满足 G2连续的缓和曲线。这条曲线在 t=1/2含有唯一的曲率极值点。利用形状参数可以方便地控制曲率极值的大小和调节曲线的形状。     

鄂尔多斯盆地地层水的配伍性研究

通过对中国图书馆分类法和中国科学院图书馆图书分类法及测绘学叙词表等相关资料的分析,确定本体中的类和定义类的语义关系,基于Protégé工具构建测绘学科信息公共本体、测绘学科分类—中图法本体及测绘学科分类—科图法本体,在构建的本体基础上基于Oracle 11g语义技术构建测绘学科分类本体库,为进一步语义检索提供基础.     

基于LBA-PP模型的年径流丰枯分类

针对年径流丰枯特性同时取决于径流本身大小和年内时程分配的特点,利用一种基于Lévy飞行策略改进的蝙蝠算法(Lévy Bat Algorithm,LBA)搜索投影寻踪模型(Projection Pursuit,PP)最佳投影方向a,提出LBA-PP年径流丰枯分类模型,并构建粒子群优化(Particle Swarm Optimization,PSO)算法-PP模型,与LBA-PP年径流丰枯分类模型对比,以云南省西洋站为例进行实例研究。结果表明LBA算法寻优能力优于PSO算法,具有较高的收敛精度、较好的稳健性能和全局寻优能力。利用LBA算法寻优PP模型最佳投影方向a,不但提高了PP模型的分类精度,而且为PP模型最佳投影方向的选取提供了新的途径和方法。LBA-PP模型同时考虑了年径流大小及年内时程分配信息,其分类结果较常规方法更科学、客观。     

Fourth graders' sensitivity to morphological context in spelling.

An important aspect of spelling development in English involves the child's ability to use morphological context to deal with one-to-many sound-spelling mappings for word endings. One case involves /z/ endings that follow long vowels, where an “s” spelling is required in the case of inflected noun and verb contexts, but an “se” or “ze” spelling is required in the case of noninflected nouns and verbs. The present study examined the ability of good and poor spellers in Grade 4 to capture these morphological distinctions in a pseudoword spelling task. Overall, the good spellers outperformed the poor spellers, and both groups were more sensitive to the inflected–noninflected noun distinction than the inflected–noninflected verb distinction. These findings underscore the importance of linguistic factors in spelling development as well as the necessity of providing due consideration to these factors in spelling instruction. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

基于Bézier曲线的地震数据三维可视化研究

针对三维地震数据资料处理和解释环节中的科学计算三维可视化问题,提出一种基于 Bézier 曲线的处理方法。通过对地震采样数据进行插值拟合或抽样取点的方式,使数据样本点的密度与成像效率保持在一定的范围内。根据地震数据信号变化规律,利用三次 Bézier 曲线插值的方式,将地震数据映射到相应的颜色向量空间,实现地震数据的三维成像处理,并在构建图像化过程中给出两种参数量化的方法。实验结果表明,该曲线插值方法的图像层次感明显,反映出的地质特征性更强。     

掺钼尾矿氯氧镁水泥免烧砖的制备

以商洛钼尾矿为试验矿样,以氯氧镁水泥为胶凝材料,进行了制砖研究。通过Mg O、Mg Cl2和钼尾矿等的混合,经搅拌、振动后制备免烧砖,研究了波美度和钼尾矿掺加量对免烧砖性能的影响,并分析了尾矿对免烧砖性能影响的机理。研究结果表明,当卤水波美度为28%,尾矿掺加量为80%时,性能较好,其28d的抗折强度和抗压强度分别为3.35MPa和9.28MPa。     

Evaluation of hydrodynamic dispersion parameters in fractured rocks

A numerical procedure to determine the equivalent hydrodynamic dispersion coefficients and Péclet number(Pe) of a fractured rock is presented using random walk particle tracking method.The geometrical effects of fracture system on hydrodynamic dispersion are studied.The results obtained from the proposed method agree well with those of empirical models,which are the scale-dependent hydrodynamic dispersion coefficients in an asymptotic or exponential form.A variance case is added to investigate the influence of longitudinal hydrodynamic dispersion in individual fractures on the macro-hydrodynamic dispersion at the fracture network scale,and its influence is demonstrated with a verification example.In addition,we investigate the influences of directional flow and stress conditions on the behavior of hydrodynamic dispersion in fracture networks.The results show that the magnitudes of the hydrodynamic dispersion coefficients are relatively smaller when the flow direction is parallel to the dip directions of fracture sets.Compressive stresses significantly reduce hydrodynamic dispersion.However,the remaining questions are:(1) whether the deformed fracture network under high stress conditions may make the scale-dependent hydrodynamic dispersion coefficients have asymptotic or exponential forms,and(2) what the conditions for existence of a well-defined equivalent hydrodynamic dispersion tensor are.They need to be further investigated.