改进的人工蜂群优化支持向量机算法在入侵检测中的应用

针对基于传统的参数优化算法在优化过程中会不同程度地陷入局部最优解的问题,在人工蜂群ABC(Artificial Bee Colony)算法的基础上提出基于交叉突变人工蜂群CMABC(Crossover Mutation ABC)算法的支持向量机SVM参数优化方法,并将其应用于入侵检测。通过引入交叉突变算子对人工蜂群算法进行改进,根据适应度值的优劣将蜂群进行划分,有效地避免了陷入局部最优,提高了收敛速度。利用标准测试函数验证了算法的有效性,并采用NSL-KDD入侵检测数据集进行仿真实验,验证了该方法的有效性。实验结果表明,该方法能有效提高入侵检测的分类性能。     

基于混合搜索的多种群人工蜂群算法

针对经典人工蜂群（ABC）算法搜索策略存在搜索机制单一、群体全局搜索与局部搜索运算耦合性较高的问题,提出一种基于混合搜索的多种群人工蜂群（MPABC） 算法。首先,将种群按照适应度值进行排序,得到一个有序队列,进而将其划分为随机子群、核心子群和平衡子群三类有序子群;其次,针对不同子群结合相应的个体选择机制与搜索策略,构建出不同的差异向量;最后,在群体的搜索过程中,通过三类子群实现对具有不同适应度函数值个体的有效控制,来增强群体全局搜索和局部搜索的平衡能力。通过对16个标准测试函数进行仿真实验并与具有可变搜索策略的人工蜂群（ABCVSS）算法、基于选择概率的改进人工蜂群（MABC）算法、基于粒子群策略的多精英人工蜂群（PS-MEABC）算法、基于符号函数的多搜索策略人工蜂群（MSSABC）算法和优化高维复杂函数的改进人工蜂群（IABC）算法共五种典型的蜂群算法进行了对比,实验结果显示MPABC具有较好的优化效果;与ABC算法相比,MPABC在求解高维（100维）复杂问题上的收敛速度提高了约23%,且求解精度更优。     

改进的混合人工蜂群算法的研究

为了解决基本人工蜂群算法（ABC）早熟收敛、容易陷入局部最优、收敛精度不高等问题,提出一种混合改进的人工蜂群算法（RABC）。首先,为了平衡ABC的全局寻优能力,在初始化种群阶段引入了混沌算子和逆向学习算子,而后为了提高局部寻优能力,在采蜜蜂的检索方程中引入了最优引导个体,最后,为了提高收敛精度和加快后期收敛速度,改进了侦察蜂的检索机制。为了验证RABC算法的收敛效果,通过在3个标准测试函数上的仿真实验,并与基本ABC算法比较,发现RABC的收敛性能有显著提高。     

增强开发能力的改进人工蜂群算法

为解决人工蜂群（ABC）算法收敛速度慢、精度不高和易于陷入局部最优等问题，提出一种增强开发能力的改进人工蜂群算法。一方面，将得出的最优解以两种方式直接引入雇佣蜂搜索公式中，通过最优解指导雇佣蜂的邻域搜索行为，以增强算法的开发或局部搜索能力；另一方面，在旁观蜂搜索公式中结合当前解及其随机邻域进行搜索，以改善算法的全局优化能力。对多个常用基准测试函数的仿真实验结果表明，在收敛速度、精度和全局优化能力等方面，所提算法总体上优于其他类似的ABC算法（例如ABC/best）和集成多种搜索策略的ABC算法（例如ABCVSS（ABC algorithm with Variable Search Strategy）和ABCMSSCE（ABC algorithm with Multi-Search Strategy Cooperative Evolutionary））。     

基于双层进化的多种群并行人工蜂群算法

针对人工蜂群算法(ABC)容易陷入早熟收敛等不足,引入文化算法双层进化结构和多种群并行进化思想,提出基于双层进化的多种群并行人工蜂群算法(PMABC)。将采蜜蜂群划分为具有不同搜索策略的子种群并行进化,平衡全局开发能力与局部搜索能力,避免算法过早陷入局部最优。采用双层进化结构,采蜜蜂群作为种群空间寻找可行解,追随蜂群作为信仰空间,记忆采蜜蜂群搜索的优质蜜源并继续搜索。将其搜索结果用于指导蜂群寻优,可加速算法收敛,提高收敛精度。通过6个经典的适应度测试函数仿真验证了该算法能够有效避免陷入局部最优,具有较快收敛速度和较高收敛精度。     

基于遗传交叉因子的改进蜂群优化算法*

针对标准蜂群算法在求解函数优化问题时易陷入局部极优点的缺陷,提出了一种基于遗传交叉因子的改进蜂群优化算法。该算法借鉴遗传算法中的选择交叉操作增加食物源多样性,通过引入交叉因子增强群体食物源的优良特性,减小陷入局部极值的可能。对几个典型的测试函数进行仿真表明,该算法较标准蜂群算法提高了全局搜索能力和收敛速度,改善了优化性能。     

改进搜索策略的人工蜂群算法

针对人工蜂群(ABC)算法存在收敛速度慢、收敛精度低的问题,给出一种改进的人工蜂群算法用于数值函数优化问题。在ABC的邻域搜索公式中利用目标函数自适应调整步长,并根据迭代次数非线性减小侦查蜂的搜索范围。改进ABC算法提高了ABC算法的局部搜索能力,能够有效避免早熟收敛。基于6个标准测试函数的仿真实验表明,改进ABC算法的寻优能力有较大提高,对于多个高维多模态函数该算法可取得理论全局最优解。与对比算法相比,该算法具有更高的收敛精度,并且收敛速度更快。     

基于改进邻域搜索策略的人工蜂群算法

针对人工蜂群算法存在易陷入局部最优、收敛速度慢的缺陷,提出一种改进邻域搜索策略的人工蜂群算法.首先,将混沌思想和反向学习方法引入初始种群,设计混沌反向解初始化策略,以增大种群多样性,增强跳出局部最优的能力;然后,在跟随蜂阶段根据更新前个体最优位置引入量子行为模拟人工蜂群获取最优解,通过交叉率设计更新前个体最优位置,并利用势阱模型的控制参数提高平衡探索与开发的能力,对观察蜂邻域搜索策略进行改进,以提高算法的收敛速度和精度;最后,将改进人工蜂群算法与粒子群算法、蚁群算法以及其他改进人工蜂群算法进行比较,利用12个标准测试函数进行仿真分析.结果表明,改进算法不仅提高了收敛速度和精度,而且在高维函数优化方面具有一定的优势.     

基于中心解的改进人工蜂群算法

为了解决人工蜂群(ABC)算法在用于函数优化时所具有的局部探索能力不强、收敛精度不高的问题,提出一种基于中心解的人工蜂群算法。该算法结合中心解和当前最优候选解的优点,并将中心解引入到跟随蜂的局部变异策略中。跟随蜂采用轮盘赌的形式,选择某些适应度值较好的蜜源,在雇佣蜂中心解的基础上深度局部寻优,并在每次迭代中逐维更新蜜源每一维度的值。为了验证该算法的有效性,选择六个基准测试函数对三种算法进行仿真对比实验。与标准ABC算法和Best-so-far ABC算法相比,改进的ABC算法的求解精度有较大幅度提高,特别是对于Rastrigin函数,两种不同维数下均达到了理论最优值。实验结果表明:所提算法在收敛速度和寻优精度上都有明显改善。     

基于维度分组交叉的自适应差分进化算法

为了解决求解高维复杂问题时存在收敛速度慢、求解精度低、容易陷入局部搜索等问题,提出维度分组交叉算法和自适应多模式并行差分进化算法。算法利用种群中各维变量之间的相关性进行维度划分,通过k个种群分别在k个维度划分上进行自适应差分进化,在种群间按维度划分进行交叉操作,从而较好实现了多种群的协同差分进化。最后对4个benchmark高维函数进行算法验证,实验结果表明,该算法在提高算法的寻优速度的同时,还有效地克服了早熟收敛等问题。     

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).