区间混合性能指标优化问题的自适应遗传算法

为了解决区间混合性能指标优化问题,在此提出了一种自适应进化优化方法。首先,基于前后代最优个体的距离,计算种群的收敛进度;然后,基于种群的多样性、收敛进度,以及进化代数,计算进化种群的交叉和变异概率;最后,将所提算法应用于室内布局这一典型的区间混合性能指标优化问题,并与其他算法比较,实验结果表明,所提算法在最优解数目、性能,以及分布性等方面均具有优越性。     

周期变异概率的免疫克隆算法

在传统免疫克隆算法的基础上提出了一种新的基于周期变异概率的免疫克隆算法,该算法进一步提高了收敛速度,有效地克服了早熟现象,很好地解决了类似高维函数优化等复杂问题.通过对比计算实验表明:种群的初始分布对该算法的性能影响很小,且对待寻优空间的全局搜索能力和局部搜索能力以及算法的稳定性与计算速率都要强于简单免疫克隆算法和自适应遗传算法等优化算法.     

一种动态分组的粒子群优化算法

针对粒子群优化算法易陷入局部最优的问题,提出一种动态分组的粒子群优化算法.通过对鸟群习性的研究,给出交互粒子的概念,并在粒子群优化过程中引入动态分组机制,将种群动态划分成多个子种群,且每次划分的子种群数目是从特定集合中随机选取,从而增加交互粒子划分到同一子种群的概率.每个子种群在收敛进化的同时,利用环拓扑结构提高种群多样性及算法搜索全局最优解的能力.实验结果表明,与其他粒子群优化算法相比,该算法具有更好的稳定性、寻优性能以及更高的收敛精度.     

动态调整概率的双重布谷鸟搜索算法

布谷鸟搜索算法是一种新兴的仿生智能算法,存在着求解精度低、易陷入局部最优及收敛速度慢等缺陷,提出了动态调整概率的双重布谷鸟搜索算法(DECS).首先,在自适应发现概率P中引入了种群分布熵,通过算法的所处迭代阶数和种群分布情况,动态改变发现概率P的大小,有利于平衡布谷鸟算法局部寻优和全局寻优的能力,加快收敛速度;其次,在...     

一种新型的动态粒子群优化算法

为了改进标准粒子群优化算法全局搜索性能,提出了一种种群动态变化的多种群粒子群优化算法。当算法搜索停滞时,把种群分裂成2个子种群,通过子种群粒子随机初始化及个体替代机制增强种群多样性,两个子种群并行搜索一定代数后,通过混合子种群来完成不同子种群中粒子的信息交流。收敛性分析表明,本文算法能以概率1收敛到全局最优解。实验结果表明,本文算法具有较好的全局寻优能力和较快的收敛速度。     

混沌映射的多种群量子粒子群优化算法

针对量子粒子群优化算法存在早熟收敛的问题,提出一种基于Logistics混沌映射变异的多种群量子粒子群优化算法（CMQPSO）,采用分段Logistics混沌映射生成初始粒子群,根据适应度值将群体分为顶层和底层种群。顶层出现聚集时才进行高斯扰动,底层种群则按概率通过Logistics混沌变异生成分布更为均匀的粒子,提高种群的多样性,从而较好地平衡了算法的局部和全局搜索能力。对测试函数的计算表明算法较QPSO等其他算法在搜索能力和收敛速度方面有明显改进。分析了算法重要参数停滞阈值[Cσ]和比例系数[S]对搜索性能的影响,给出合理的取值范围。     

基于扩散机制的双种群粒子群优化算法*

为了避免标准粒子群优化算法（PSO）过早收敛的缺点,把热力学中的扩散现象引入到PSO算法的改进当中,提出了基于扩散机制的双种群粒子群优化算法(DPSO)。DPSO算法中定义了粒子的扩散能、种群的温度和粒子的扩散概率三个概念,两个群体中的粒子在进化过程中根据粒子的扩散概率被选入到各自种群的扩散池中,从而实现两个种群之间信息的交换和共享。通过解决典型的多峰、高维函数优化问题来证实DPSO算法的有效性,实验结果表明DPSO比标准PSO具有更高的性能。     

一种改进遗传算法在生产车间设备布局中的应用

生产系统的设备布局设计是一个组合优化的问题。具有非线性,N P难等特性,常规方法较难以求解。文章通过创建生产系统设备布局的数学优化模型。引入了小生境技术,保持了种群的多样性。并且利用精英选择机制,自适应交叉和变异概率等手段,在使种群保持多样化的同时,增强了算法的全局和局部搜索能力,协调了遗传算法大范围粗糙搜索和小范围精细搜索之间的平衡,有效改善了早熟和过早收敛问题,并通过实例验证了其有效性。     

基于异构多种群策略的动态概率粒子群优化算法

结合动态概率粒子群优化算法(DPPSO)特点,针对传统的单种群粒子群优化算法易陷入局部最优、收敛速度较慢的缺点,文中提出一种基于异构多种群策略的DPPSO.该算法在进化过程中保持多个子种群,每个子种群以不同的DPPSO变体进行进化,子种群之间根据一定规律进行通信,从而保持整个种群内部的信息交流,进而协调DPPSO的勘探和开采能力.通过典型的Benchmark函数优化问题测试并分析基于异构多种群策略的DPPSO性能,结果显示,使用该策略的算法收敛速度较快,稳定性有较显著提高,具有较强的全局搜索能力.     

带密度加权的自适应遗传算法

为了改善传统自适应遗传算法收敛速度慢、易陷入局部最优解的情况,提出了带密度加权的自适应遗传算法. 该算法基于种群的分布密度,动态调整遗传算法的交叉概率和变异概率,并且在算法中使用了保留最佳个体法. 实验结果表明：该算法在破坏种群局部稳定性、跳出局部极值的同时,又能以较快的速度收敛于全局最优,提高了算法的实用性和鲁棒性.     

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).