天然气发动机空燃比智能控制策略的研究

该文详细介绍了基于神经网络的控制器在天然气发动机空燃比中的控制实现，并用Matlab进行了仿真，仿真结果表明，其控制效果优于基于PID的控制器，所研究的基于单神经元控制器的学习算法在工程上易于实现，在发动机空燃比控制的工程应用中有很好的前景。     

带参数辨识的自适应二阶滑模观测器PMSM无传感器矢量控制

针对表贴式永磁同步电机无位置传感器矢量控制系统, 提出一种具有电机参数在线辨识的基于Super-twisting algorithm的自适应二阶滑模观测器.在两相静止坐标系下,将模型参考自适应方法与基于Super-twisting algorithm的二阶滑模方法相结合,实现反电动势的准确估计.采用李亚普诺夫理论证明观测器的稳定性,并由李亚普诺夫稳定性方程推导定子电阻和转子转速的自适应律.在同步旋转坐标系下,采用二阶滑模观测器估计永磁磁链,并将其输入位置跟踪观测器估计转子位置.该算法充分抑制了滑模抖振,同时避免了低通滤波和相位补偿环节的使用,转子位置检测不受定子电阻和永磁磁链变化的影响,具有较强的鲁棒性.仿真结果验证了所提出算法的有效性.     

汽油机非线性卡尔曼滤波暂态进气量估计及空燃比控制

暂态工况下缸进气量的准确估计是提高发动机空燃比控制精度的有效措施之一,为此本文提出一种基于无迹卡尔曼滤波的暂态缸进气量估计算法,并利用估计的缸进气量设计了一种前馈-反馈空燃比控制器.MATLAB环境下的仿真实验给出了所提出的算法与现有进气量估计算法的比较,同时基于暂态气量估计的空燃比控制仿真实验验证了估计的有效性.论文与现有成果的区别在于:一是暂态进气量估计模型不仅包含了歧管压力动态还考虑了曲轴角速度动态,并采用了基于非线性辨识的均值模型;二是考虑了泵气波动的影响,采用了移动平均值法的数字滤波器对泵气波动进行滤波;三是采用无迹卡尔曼滤波算法对歧管压力和曲轴角速度进行估计.     

四旋翼飞行器的自适应二阶滑模控制

针对四旋翼飞行器参数变化的姿态控制问题,将自适应光滑二阶滑模控制方法应用于四旋翼飞行器控制系统.对于参数变化引起的模型不确定性部分采用滑模干扰观测器进行补偿,对姿态系统设计自适应光滑二阶滑模控制器,有效地减弱传统滑模控制的抖振,控制器参数的在线调整提高了系统的控制精度.基于Lyapunov理论证明了系统的有限时间稳定.数字仿真和实验结果都验证了所提控制方法的有效性.     

基于二阶滑模控制理论的新型滚转稳定控制器

为了降低导弹飞行中不确定因素等对弹体滚转稳定的影响,设计两种新型基于二阶滑模控制理论的滚转稳定控制器,即基于二阶滑模控制理论的控制器与基于super-twisting算法的控制器.第一种控制器能够稳定地控制滚转角收敛至期望值,而第二种控制器不仅能够有效降低气动参数不确定性对弹体滚转控制造成的影响,而且能控制滚转角速度在有限时间内收敛至期望值,并有效抑制滑模算法固有的抖振现象.通过构造Lyapunov函数对所设计控制器的稳定性进行理论验证,将所设计的两种控制器与基于线性滑模控制理论的控制器和基于终端滑模控制理论的控制器进行仿真对比,并考虑不同攻角条件下气动参数的影响,以验证所设计的控制器的有效性、快速性和鲁棒性.     

二阶滑模控制在直流无刷电机转速调节中的应用

针对受参数不确定和负载扰动影响的直流无刷电机的鲁棒速度控制问题,采用二阶滑模控制中的超螺旋算法设计速度控制器。控制器将不连续控制作用在滑模量的二阶微分上,不但保持了传统一阶滑模的性能,而且消弱了系统抖振。仿真结果表明,算法对负载和参数的变化具有很强的鲁棒性,有效地消弱了传统滑模的抖振现象。     

二阶切换线性系统的滑模控制

当前,切换系统的稳定控制问题作为控制领域的一个研究难点,引起了学术界和工业界的广泛关注.该文针对二阶切换线性系统,考虑切换时对象特性的变化,将其转化为一类特殊的非线性系统,并基于滑模控制理论,设计出适用于二阶切换线性系统的滑模控制器.最后通过具体的实例仿真验证、结果对比,表明滑模控制器比传统PID控制器在二阶切换线性系...     

不确定欠驱动系统的高阶自适应Super-Twisting滑模控制

为实现一类不确定欠驱动系统在未知干扰情况下的鲁棒控制,针对传统滑模控制中存在的抖振问题,提出一种基于二次型Lyapunov函数的二阶Super-Twisting自适应滑模控制策略.首先,控制器的不连续项采用二阶Super-Twisting算法,将不连续控制作用在滑模量的二阶导数.然后,针对滑模面受不确定干扰影响的情况,为调节参数设计一种自适应律方法,该方法不受传统二阶滑模控制中干扰项的一阶导数边界已知的条件限制,保证滑模面在有干扰情况下的收敛,削弱控制器输入的抖振现象.最后,以两轮自平衡车为实验对象验证该方法,并与传统滑模及普通二阶滑模方法做仿真对比.仿真结果表明文中所提的二阶自适应滑模控制方法在控制效果和降低抖振方面表现更优.     

悬臂式掘进机器人截割臂建模与二阶滑模控制器设计

根据悬臂式掘进机器人截割工艺和结构特点,建立了截割臂动力学模型.将一种基于有限状态结构的二阶滑模控制扩展到多输入多输出系统中,在无速度观测器的情况下,保证了滑模量及其导数在有限时间收敛到零.算法消弱了传统滑模控制中的抖动问题,提高了控制系统精度.利用提出的多输入多输出二阶滑模控制算法,设计了截割臂控制器.通过仿真和实验,证明了算法的有效性.     

二阶动态滑模控制在磁悬浮控制系统中的应用

磁悬浮是典型的非线性、不稳定系统.为了实现其控制,本文采用了一种结合二阶滑模和动态滑模两种设计思想的二阶动态滑模控制器的设计方法,首先推导了磁悬浮系统的线性化状态空间模型;然后针对被控对象设计了二阶动态滑模控制器;最后与普通滑模控制器进行对比仿真试验.仿真结果表明,所设计的二阶动态滑模控制器在使小球快速稳定到达平衡点的同时,大大削弱了普通滑模控制器中存在的严重抖振现象.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

法律信息库系统

本文分析了法律数据库的结构和特点，介绍了采用面向对象设计方法和超文本数据库技术开发和实现法律信息库系统将作为重要网络资源之一为不同用户进行法律咨询服务。     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

International Journal of Automation and Computing Table of Contents

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Information for authors

正SCIENCE CHINA Information Sciences(Sci China Inf Sci),cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press,is committed to publishing highquality,original results of both basic and applied research in all areas of information sciences,including computer science and technology;systems science,control science and engineering(published in Issues with odd numbers);information and communication engineering;electronic science and technology(published in Issues with even numbers).Sci China Inf Sci is published monthly in both print and electronic forms.It is indexed by Academic OneFile,Astrophysics Data System(ADS),CSA,Cabells,Current Contents/Engineering,Computing and Technology,DBLP,Digital Mathematics Registry,Earthquake Engineering Abstracts,Engineering Index,Engineered Materials Abstracts,Gale,Google,INSPEC,Journal Citation Reports/Science Edition,Mathematical Reviews,OCLC,ProQuest,SCOPUS,Science Citation Index Expanded,Summon by Serial Solutions,VINITI,Zentralblatt MATH.     

Erratum to: Fast global kernel fuzzy c-means clustering algorithm for consonant/vowel segmentation of speech signal

正Erratum to:J Zhejiang Univ-Sci C(ComputElectron)2014 15(7):551-563doi:10.1631/jzus.C1300320The original version of this article unfortunately contained mistakes.Algorithm 6 should be as follows:Algorithm 6 FGKFCM-F clustering Input:(1)X={x_1,x_2,…,x_N},,x_iR~d,i=1,2,…,N,the dataset;(2)C,1C≤N,the number of clusters;(3)ε0,the stopping criterion;     

Journal of Zhejiang University-SCIENCE C (Computers & Electronics) Total contents

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A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.