改进布谷鸟搜索SVM在财务风险评估中的应用

针对一种新型智能进化算法--布谷鸟搜索算法提出了基于多群体并行搜索和自适应步长的改进方法。将改进后的方法引入支持向量机参数优化中,提出了基于改进后布谷鸟搜索算法优化支持向量机模型参数的方法并将其应用于上市公司财务风险评估中,有效提高了财务风险模型的分类性能。仿真结果发现：改进的布谷鸟搜索算法用于优化支持向量机参数不仅有效提高了上市公司季度财务数据分类预测精度,而且相较改进之前的布谷鸟搜索算法、遗传算法和粒子群算法具有更快的收敛速度和稳定性。     

基于感知模糊自适应蚁群算法的非线性PID控制

随着系统复杂度的提高和对象不确定性因素的增加,为克服线性PID动态性能和稳态性能差的缺陷,分析了非线性PID控制器各控制参数对误差的理想变化过程,构造非线性PID控制器。由于增益参数大量增加,传统参数优化方法不再适用,在分析蚁群算法的基础上,提出了基于感知自适应蚁群算法,并加入模糊自适应信息素更新机制,用于优化非线性PID控制器的设计方法。通过仿真实验将该控制器与基于蚁群算法的非线性PID控制器和基于蚁群算法、Z-N法的PID控制器进行对比,并对控制性能和收敛性能进行了分析,结果表明该算法有效克服了传统蚁群算法收敛速度较慢、容易陷入局部最优而停滞的缺陷,该控制器具有更好的动态性能和稳态性能。     

基于布谷鸟算法的混凝土搅拌站称重系统优化

模糊PID控制（FPID）在混凝土搅拌站称重系统常被使用，针对FPID不能实时更新比例因子的问题，提出基于布谷鸟算法的模糊PID控制方法（CFPID）改进系统动态性能。首先，该文介绍了称重系统主要构成；其次，建立了称重系统的数学模型并设计FPID控制器；再采用布谷鸟算法优化FPID控制器的比例因子；最后，进行对比实验验证。结果表明，优化后的系统超调量更小、调节时间更短。     

基于灰狼优化算法的PID控制器设计

为了寻找最佳的比例、积分和微分（PID）控制器增益因子,使系统输出尽可能接近参考输入信号的变化,使得控制系统的时间加权绝对误差积分最小,提出了基于灰狼优化算法（GWO）进行PID控制器增益因子优化设计的方法。为了评估该方法的性能,针对设定点跟踪设计目标,通过使用3种基准线性数学模型进行仿真测试,并与粒子群优化算法（PSO）、引力搜索算法（GSA）得到的仿真结果进行了比较。仿真结果表明,基于灰狼优化算法的最优参数PID控制器比基于其他算法的性能更好,最优值更佳。     

航空发动机分数阶PID控制器的参数自整定方法

控制器作为航空发动机的大脑,是保障发动机正常运行的核心部件,随着对发动机控制器精度和时效性的要求越来越高,传统PID控制器的性能亟需进一步提升.本文提出了改进的分数阶PID离线和在线参数整定方法,应用于涡扇发动机推力的控制中.首先,利用Caputo分数阶微积分定义建立分数阶PID模型,实现时域上的数值计算;其次,基于对数正态分布提出了改进的布谷鸟算法,实现了分数阶PID离线参数整定;然后,结合RBF网络设计参数线上整定方法,解决了参数在线整定问题;最后将相关理论应用于发动机推力的控制中,结果表明,相比其他几种优化算法,改进的布谷鸟优化算法对分数阶PID控制参数整定效果最好;利用RBF神经网络对分数阶PID进行在线整定时控制效果稳定,且分数阶PID的控制效果优于传统的PID控制,能提高对推力的控制能力.     

基于蚁群神经网络的工业自动化PID参数优化

针对常规方法无法获得最优PID控制器参数的缺点,提出一种基于蚁群神经网络的PID控制器参数优化方法（ACO-RBFNN）。ACO-RBFNN将PID控制器的3个参数作为RBF神经网络的输入,系统输出为RBF神经网络期望输出,通过蚁群算法对RBF神经网络的参数进行优化,并通过RBF神经网络构造参数自学习的PID控制器,从而实现PID控制器参数在线优化。仿真实验结果表明,基于ACO-RBFNN的PID控制器可以得到令人满意的控制效果,可以应用于工业自动化控制系统的PID控制器参数优化。     

基于人群搜索算法的PID控制器参数优化

关于PID控制器在工业控制领域应用优化问题,PID参数优化成为工业自动化研究的热点.PID参数优化对于系统的稳定性、可靠性和快速响应等特性有着重要的意义.为了改善和优化PID控制器性能,提出一种人群搜索算法(SOA),以PID三个参量为搜寻队伍,以误差绝对值和控制输入平方项的时间积分作为优化目标,经过迭代寻优计算得到系统最优控制量.通过对比遗传算法和粒子群算法PID参数优化,仿真结果表明,改进算法提高了系统的控制精度,系统响应速度快,鲁棒性好,为控制系统PID参数整定提供了参考.     

作业车间调度问题的布谷鸟搜索算法求解

布谷鸟搜索算法是一种新型元启发式优化算法,该算法受到自然界中布谷鸟的巢寄生行为启发而提出。首先分析了布谷鸟搜索算法的仿生原理和数学描述,采用基于工序的编码方式对最小化最大完工时间的作业车间调度问题进行布谷鸟搜索算法求解。通过典型算例进行仿真实验,测试结果表明布谷鸟搜索算法求解作业车间调度问题的可行性和有效性,优于萤火虫算法和基本粒子群算法,是解决生产调度问题的一种有效方法。     

基于粒子群优化的PID控制器设计与应用

研究优化控制器设计问题,工业过程控制中广泛使用的PID控制器,参数的选取可等效为优化问题.针对PID控制器应用于实际的自动电压调节器(AVR)系统,为了有效地寻找AVR系统的最佳PID控制器参数,提出一种基于粒子群算法的PID参数优化策略.通过建立粒子群优化的PID控制器参数模型,在控制过程中将PID参数(比例、积分、微分)作为粒子群中的粒子,采用控制误差绝对值时间积分函数作为优化目标,在控制过程中动态调整PID的三个控制参数,从而进行PID控制参数的实时优化.仿真结果表明PID控制器可以获得较好的控制性能指标,进而改善AVR系统的瞬时响应特性,具有一定的实用价值.     

免疫最优PID控制器设计与应用

以基于欧氏距离和精英交叉的人工免疫算法(DKBAIA)为基础,提出了一种新的最优PID控制器的设计方法。这种方法的核心是以ITAE性能准则为目标函数,采用DKBAIA去调整和优化PID控制器参数,以获得最优的目标函数值,进而获得最优的PID控制器。所设计的这种控制器称为DKBAIA—PID控制器。将该控制器用于控制智能仿生人工腿的执行电机中,并进行计算机仿真实验,结果表明:这种基于免疫算法的最优PID控制器具有良好的动态和稳态性能。     

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).