多周期非自衡系统预测控制研究

为使预测控制能够运用于具有不同输出周期的多变量非自衡系统，对这类特殊系统和一般预测控制算法进行了研究，提出了基于多周期的多变量非自衡预测控制，并通过对环境试验设备温度湿度控制系统的仿真实验，证实了此算法的有效性和实用性。     

多变量非自衡系统预测函数控制研究

针对多变量非自衡系统，本文推导出基于脉冲响应系数模型的多变量非自衡预测函数控制算法。通过对环境试验设备温度湿度控制系统的仿真实验，证实了此算法的有效性和实用性。     

一类非自衡对象的改进动态矩阵控制

针对DMC算法无法直接对非自衡对象进行控制的特点，推导出了一种基于非自衡对象阶跃响应的改进动态矩阵控制算法。该算法对DMC预测模型的误差，采用实际输出的变化趋势校正。仿真结果表明，所提出的算法对于设定值有良好的跟踪特性，具有很强的抗干扰能力和快速调节性能，验证了本文方法对非自衡对象控制的有效性。     

神经网络非线性多步预测逆控制方法研究*

提出了基于多步预测控制方法的多变量非线性神经网络逆控制方案。利用预测模型对系统动态特性进行预测,使用一个带有时延因子的前馈神经网络作为控制器,利用多步预测性能指标对其在线训练,实现神经网络逆系统;在多步预测过程中还对每一步的预测误差进行预测,以实现预测误差补偿。将所提出的控制算法用于锅炉这种大滞后非线性对象的控制,仿真实验证明,该控制策略具有良好的解耦和动态跟踪性能。     

基于单变量与多变量系统的模型预测控制研究

为充分验证模型预测控制算法在解决工业过程中单变量与多变量系统控制问题的先进性,研究了以单容水箱与精馏塔为典型系统的模型预测控制算法的实现过程.结合上述实际系统,阐述模型预测控制算法中预测模型、滚动优化以及反馈校正环节的具体含义以及理论推导过程.利用西门子PCS7提供的集散控制系统(DCS)为平台,对单变量与多变量系统进行模型预测控制系统设计与算法开发,从仿真与实际控制两方面体现模型预测控制算法的先进性与实用性.     

广义预测控制：理论、算法与应用*

本文简要介绍了广义预测控制基本方法及其近年来提出的改进广义预测控制算法，并对非互性系统广义预测控制、多变量系统广义预测控制、广义预测控制的稳定性与鲁棒性分析作了进一步讨论，最后，概述了广义预测控制在工业中的应用和广义预测控制的进一步研究方向。     

串联系统的多前馈-反馈广义预测控制

为了充分利用对象的可知信息以实现串联系统的最优控制，提出了串联系统的多前馈-反馈广义预测控制算法，该算法把系统的可知外部扰动作为系统的多输入变量，把可测量的中间变量作为系统的多输出变量，运用多变量广义预测控制的思想给出了算法的控制结构。实现了前馈控制与反馈控制的有机结合，仿真结果表明，该算法能极大地改善串联系统的抗干扰性和鲁棒性。     

动态矩阵控制在工业锅炉燃烧系统的应用

工业锅炉燃烧过程可以合理简化为一个双输入双输出的多变量系统。为提高动态矩阵控制算法 的实用性，对一般的控制算法进行改进，采用简化后的预测前馈控制，使计算量大为减少。     

时滞过程的多变量广义预测控制算法

文章提出了用广义预测控制算法解决多变量系统的时滞问题的一种新的方案。该方法将时间滞后因子自然纳入系统的控制机制,可完全无误差的实现对时滞系统的控制,克服了传统近似法解决时滞所带来的误差问题。这种广义预测控制算法能有效的控制开环不稳定非最小相位系统,并有良好的解耦性能．在跟踪性．鲁棒性和抗下扰性方面都得到了很好的控制效果。     

神经网络解耦预测函数控制

结合解耦思想研究多变量系统预测函数控制。通过引入神经网络补偿环节，对多变量系统解耦，在此基础上，对解耦后各子系统进行单变量预测函数控制，以确定各个控制量。同时基于系统脉冲传递函数，得到单变量PFC控制器的显式表达式。仿真表明，该算法有较好的跟踪特性，对解决多变量系统的优化和控制具有一定的适用性。     

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).