基于变异的检测器生成算法研究

为提高基于免疫的网络入侵检测系统中检测器的生成效率,减小计算量.对Forrest的否定选择算法(NSA)进行改进,提出候选检测器集的生成不再采用随机方式,而通过对两个数据集(一是已有的合格检测器集,二是自我数据集)进行变异来产生,即利用部分已有的检测结果反馈生成成熟检测器.改进算法提高了候选检测器成为成熟检测器的比率,实验结果表明了算法的有效性.     

改进的混沌否定选择算法

针对检测器集生成速率不高的问题,提出一种改进的混沌否定选择算法。由于Logistic映射折叠次数有限,采用自映射产生的混沌序列,改进混沌二值序列的产生方法。实验结果表明,该算法具有较好的混沌特性,能有效提高检测器集的生成速度,较好地覆盖检测空间,安全性较强。     

一种改进的否定选择算法在入侵检测中的应用

有效的检测器生成算法是入侵检测的核心问题。针对现有算法存在检测率低、匹配阈值固定、检测器集合庞大等问题,通过对人工免疫系统中否定选择算法原理的分析,提出一种生成最有效检测器集的变阈值模糊匹配否定选择免疫算法,并将该算法应用到入侵检测系统中。算法采用随机生成和基因库相结合的候选检测器生成机制,在保证检测器多样性的同时,提高了候选检测器成为成熟检测器的比率。为了消除冗余检测器的产生,提高检测器集的检测效率,算法在模糊匹配的基础上生成有效检测器集。同时,匹配阈值可变,可大幅降低黑洞数量。实验结果表明,该算法提高了入侵检测率,降低了虚警率,整体检测性能较好。     

新的否定选择算法及其在疾病诊断中的应用

针对现有的否定选择算法存在检测率较低,检测器集合过大等问题,提出了一种结合非自体信息和二次移动的实值否定选择算法(NTMV-detector)。该算法基于训练集中的非自体和随机的方法生成候选检测器中心。二次移动的主要思路是:如果候选检测器中心与成熟检测器匹配,把它移出成熟检测器集;然后通过离候选检测器中心最近的两个自体来微调检测器的位置,确定检测器半径。实验证明,该方法可以有效地提高疾病诊断的诊断率,降低误诊率。     

基于二维混沌映射的免疫算法研究

网络环境的不断变化和计算机病毒的不断变异,使得计算机病毒越来越难以防范和检测.针对当前计算机病毒检测过程中检测器的生成效率问题,提出了一种基于生物免疫机制和混沌理论的检测器生成算法.该算法利用改进的否定选择算法来提高有效检测器的生成效率,以及检测器的覆盖率.通过实验,表明该算法的性能得到有效地改善,大大减少了不可避免的...     

基于局部线性嵌入的免疫检测器优化生成算法

网络安全已上升到国家安全战略层面,入侵检测技术是其重要的组成部分,已得到广泛关注.在基于免疫的入侵检测研究中,针对传统实值否定选择算法不利于高效分析数据而造成的检测器生成速度慢、检测效率低等问题,引入局部线性嵌入算法,借鉴其能对高维数据进行映射降维的特点,提出一种基于局部线性嵌入的免疫检测器优化生成算法,利用局部线性嵌入对高维数据预处理优化降维,并结合实值否定选择算法生成检测器.将该算法用于检测模型,从而提升检测器的生成速率,并可保证生成的检测器高效地处理高维数据.该算法在降维前后可保证样本的局部线性结构不变,具有可变参数少、计算时间短的特点.实验结果表明,所提出算法在显著提高检测器生成速率和对数据检测效率的基础上,检测性能也表现出很好的水平.     

一种可变阈值检测器生成算法的研究

在构造人工免疫系统中,如果能自动调节生成检测器的大小,从而利用较少的检测器,实现对较大"非自体集"的检测,就可从根本上提高系统效率.本文通过分析人工免疫系统中的主要算法--否定选择算法,以及检测器产生漏洞的原因,提出了一种可变阈值的检测器生成算法.与传统的否定选择算法相比,该算法大大减少了漏洞,使检测效率得到提高.     

改进的否定选择算法及其在入侵检测中的应用

否定选择算法(Negative Selection Algorithm,NSA)作为人工免疫系统的典型算法被广泛应用于入侵检测中.针对传统否定选择算法在处理入侵检测问题时出现的准确率低、误报率高以及检测器集合冗余度高等问题,提出了一种改进的否定选择算法并将其应用到入侵检测中.其主要思想是:首先通过密度峰值聚类算法对非自体抗原进行聚类,生成一类已知检测器,该检测器可检测已知入侵行为;然后定义异常点并将其优先作为候选检测器中心,计算和生成未知检测器,该检测器可检测未知入侵行为,以此降低检测器生成的随机性.在实验阶段,选择准确率(Accuracy,AC)和误报率(False Alarm,FA)作为评价指标.分别在KDDCUP99和CSE-CIC-IDS2018数据集上进行了仿真实验,实验结果表明,所提算法在这两种数据集上均有较低的误报率和较高的准确率,这验证了其具有较好的检测效果.     

基于决策树的主从结构的Self集构造算法

针对基于计算机免疫的入侵检测系统中所面临着"不完全Self集"的问题,设计了基于决策树的主从结构的Self集构造算法.将决策树引入到传统的否定选择算法中,通过决策树把经过免疫耐受淘汰后的候选检测器进行重新分类,并将满足设定条件的候选检测器集合构造"从Self集",实现Self集的动态扩充,最后利用"匹配矛盾"淘汰"从Self集"中不合格的元素.实验分析结果表明了该算法的有效性,改善了检测器识别性能.     

一种分段检测器集合生成算法的研究与实现

目前大多数入侵检测算法的研究均用于提高系统检测的准确率和对非法抗原的覆盖率,缺乏对提高算法检测速度的研究。针对这一问题,提出一种新的基于否定选择的检测器生成算法,利用分段的方法,先将候选检测器集合的大小利用求解递归公式计算出来,再用求解序号随机生成检测器。实验表明,该算法的时间效率得到显著提高,并具有实际的工程应用价值。     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).