中央空调房间温度智能PID控制的仿真研究

中央空调房间温度控制系统是一个复杂系统,针对一次性整定得到的PID参数难以保证系统控制始终处于优化状态和良好的品质特性,提出了参数自整定方法,通过实时改变PID参数从而保证控制系统的优良品质。结合粒子群优化算法和模糊控制以及传统PID控制各自的优势,设计了一种新的自适应模糊PID控制器。鉴于PID控制器的性能完全依赖于其参数的整定和优化,采用粒子群算法离线优化PID参数,并利用模糊控制在线调整PID参数,以取得良好的控制效果。利用Matlab软件进行了数字仿真。仿真结果表明,方法调节精度较高,调节迅速,超调小,具有一定的可行性。     

进化规划模糊算法在PID控制中的应用

针对非线性控制系统,利用进化规划模糊算法,对PID控制器规则基的参数进行离线优化,优化后的模糊控制规则可对系统实现实时控制。该控制算法无需任何先验知识和量化因子,具有很强的数据挖掘能力,且模糊规则基的寻优速度较快。通过对非线性系统进行仿真,验证了该算法的有效性,与传统固定参数PID控制方法及遗传算法整定参数PID控制方法相比,明显地提高了系统的稳定性和动态性能。     

基于MATLAB的模糊自整定PID参数控制器的设计与仿真

针对在复杂系统中实现自整定参数的PID控制问题,介绍了一种基于模糊控制原理的PID参数自整定控制器的设计,并把MATLAB中的Fuzzy Toolbox和SIMULINK有机结合起来,方便的实现了该模糊自整定PID参数控制系统的计算机仿真.     

模糊自整定PID温度控制系统的建模与仿真

针对炒茶机的加热控制系统跟踪设定的温度值滞后、自动调节加热装置实时性差的问题,设计一种模糊自整定比例积分微分(PID)参数控制器。采用PID控制和模糊控制算法相结合的方法,实现模糊控制对PID参数的调整。利用Matlab在Simulink中建立模型,并对该控制器进行仿真分析。结果表明,模糊PID自整定控制器的超调量 ≈1%,稳态误差es=0。该方法可提高温度控制系统的性能。     

基于模糊RBF神经网络的PID及其应用

针对传统的PID控制器参数固定而导致在控制中效果差的问题,提出一种基于模糊RBF神经网络智能PID控制器的设计方法。该方法结合了模糊控制的推理能力强与神经网络学习能力强的特点,将模糊控制与RBF神经网络相结合以在线调整PID控制器参数,整定出一组适合于控制对象的kp, ki, kd参数。将算法运用到电机控制系统的PID参数寻优中,仿真结果表明基于此算法设计的PID控制器改善了电机控制系统的动态性能和稳定性。     

基于MATLAB的模糊自整定PID参数控制器的设计与仿真

针对在复杂系统中实现自整定参数的PID控制问题,介绍了一种基于模糊控制原理的PID参数自整定控制器的设计,并把MATLAB中的FuzzyToolbox和SIMULINK有机结合起来,方便的实现了该模糊自整定PID参数控制系统的计算机仿真。     

参数自整定模糊PID控制在烘干炉中的应用

将参数自整定模糊控制与传统PID控制相结合.实现了对PID参数的在线自整定,克服控制系统的大滞后、非线性等不利因素的影响.该控制器在烘干炉温度控制系统中,取得了良好的控制效果.     

模糊自适应PID控制器在足球机器人中的应用

传统的PID控制器结构简单、实现简单、控制效果良好,所以在足球机器人中广泛应用.但由于机器人机械加工精度问题,每个足球机器人都存在个体差异,很难得到一致的PID控制参数.本文提出了一种基于模糊控制理论的足球机器人控制系统,针对传统PID控制器的特点,将摸糊控制技术引入到PID参数自整定过程中,根据不同情况在线自整定PID参数.通过和传统的PID控制器比较,模糊自适应PID控制器具有具有灵活性好,控制适应性强,动态、静态性能好等优点.在MIROSOT机器人上验证了该控制器的有效性和实用性.     

模糊自整定PID算法在伺服控制中的应用研究

模糊自整定PID算法的控制系统同时具有PID控制和模糊控制的优点,可满足伺服电机随动控制的高性能跟踪任务需求.基于模糊自整定PID控制原理和模糊控制的基本概念,研究了PID参数模糊自整定模糊化、模糊推理、清晰化这三个步骤的任务内容、实现方法和程序函数,并设计了基于该算法的实时伺服控制软件.试验结果表明,基于该算法的伺服控制系统在不同跟踪速度下均具有较高的控制精度和良好的动态性能.     

模糊自整定PID控制器的设计与仿真

常规PID控制器因结构简单、鲁棒性好、参数调整方便等,常被用于工业过程控制.但其参数整定是在获取被控对象数学模型的基础上根据一定的规则来确定的,难以适应复杂多变的控制系统.针对其参数整定效果不良、调试时间长、对被控对象适应性差等缺点,将模糊控制与PID控制相结合,设计了模糊自整定PID控制器.在常规PID控制器基础上,根据相应的模糊规则进行模糊推理,实现PID参数的在线自整定.仿真结果表明,模糊自整定PID控制器,不仅具有模糊控制快速、适应性强等优点,又有PID控制精确度高的特点,使系统有较好的控制作用,因此具有较好的工业应用前景.     

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).