非线性Hammerstein系统辨识的动态分离方法

利用同幅值的M序列和逆M序列作为输入信号, 对Hammerstein模型中的线性动态部分进行分离处理, 通过辨识得到一个线性动态模型. 基于此线性模型, 依据系统的测量输出重构出系统的中间输入. 最后由系统的测试输入和中间输入估计出非线性部分的参数. 仿真结果表明本方法的有效性.     

基于小波分析的分数阶系统辨识信号降噪的变尺度阈值方法

在目前愈来愈被关注的分数阶控制研究中,系统辨识的分数阶理论与方法是一个重要方向,其中,辨识实验检测数据的降噪是必须关注的课题。基于小波分析理论与方法,首先对系统辨识中常用的以伪随机二进制序列(PRBS)激励的分数阶系统输出信号及其干扰噪声的特性进行分析讨论,在此基础上,为克服常规阈值降噪法的局限性,提出了针对多层小波分解系数进行非线性变尺度量化改造的算法,进而形成了一种分数阶系统辨识信号降噪的变尺度阈值方法。仿真实验表明,该方法能够将噪声干扰削减到满意的水平,对于不同的信噪比情形具有很好的适用性。该研究旨在为进一步的辨识算法设计提供参考,以提高辨识精度。     

连续Hammerstein模型参数估计方法

本文提出一种辨识连续Hammerstein模型参数的方法,该方法利用不同幅值的M周期序列作为系统的输入,通过DFT变换,离析出线性子系统的连续模型,并由频域辨识法及时域辨识法直接估计出连续模型的参数和非线性特性的系数。数字仿真结果表明本算法是可行且有效的。     

系统辨识在水压仿真器试验建模中的应用

水压仿真器作为一种特殊电液压力伺服系统,通过控制伺服阀的开口直接控制工作腔的压力变化,很难通过理论方法进行建模。应用系统辨识方法对水压仿真器的数学模型进行了研究,首先设计能使系统稳定的简单闭环,再对系统施加合适的输入信号,记录系统的输出信号进行试验建模,最后推导出被控对象的数学模型。经过验证,辨识模型基本能够反映实际系统的特性,这种辨识方法是研究水压仿真器或相似压力伺服系统特性的一种可行方法。     

基于递推最小二乘法的温箱系统辨识

温箱在生活中应用越来越广泛,对于温箱的精确控制已成为一项重要课题,所以对于温箱模型的分析和确定十分重要。以温箱为辨识对象,在温箱热稳定的基础上给温箱输入M序列辨识信号来获取辨识数据。采用递推最小二乘法对温箱进行辨识并按照残差定阶法对温箱系统进行定阶、定型。最后在MATLAB中仿真并验证。     

基于余弦型伪随机信号的伺服阀辨识研究

针对M序列伪随机信号在电液伺服阀在线非参数辨识中存在状态有限的问题,提出将具有连续状态的余弦型伪随机信号作为输入信号,证明在不同信号幅值下余弦型伪随机信号具有最佳自相关特性,用于系统辨识中精度不受测量误差信号、直流分量信号的影响,具有精度高计算量小的优点,在相同序列长度下可以测试更多频率点.研究了在电液伺服阀非参数辨识中的余弦伪随机信号参数的选择方法,试验证明了余弦型伪随机信号在系统辨识中的优点.     

一种核反应堆功率控制器设计方法

介绍用最优传递函数方法设计反应堆功率控制器的方法和步骤。在系统的指令信号为单位阶跃信号下,运用MATLAB中的Simulink对系统进行了仿真,并比较不同的性能指标加权因子对系统动态特性的影响。仿真结果表明:控制器能使系统控制特性明显改善,是一种有效的设计方法。     

辨识系统单位脉冲响应的一种方法

引言在系统辨识中,系统单位脉冲响应的辨识得到了广泛的应用。这不仅因为单位脉冲响应本身就是系统的非参数模型,而且在多步最小二乘法辨识系统参数模型中,也要首先辫识系统单位脉冲响应。单位脉冲响应辨识一般有五种方法:最小二乘法、相关分析法、m序列法、逆重复M序列法和递推最小二乘法。其中逆重复M     

多功能伪随机信号相关仪及冷轧机控制系统在线辨识

本文介绍了根据系统在线辨识原理设计的伪随机信号相关仪,还讨论了采用多周期逆重复m序列,配合实时二项式加权平均消除系统直流漂移对测试脉冲响应函数的影晌;对系统施加一个周期预扰动,消除系统被扰后初始输出非平稳造成的不良影响;将两个相互相差二分之一半周期的逆重m序列作为独立序列,来辨识多维系统.(并用实验证明了以上提高辨识准确度的措施所获得的效果以及所扩大的功能.最后介绍了冷轧机控制系统的在线辨识与在线调整.     

遗忘因子法参数辨识及其在Matlab中仿真实现

介绍了基于MATLAB／Simulink的使用遗忘因子法进行参数辨识的设计与仿真方法。首先简述参数辨识的概念和遗忘因子法的基本原理，然后介绍如何采用Simulink建立系统的仿真对象模型和运用MATLAB6．5的M语言编写遗忘因子递推算法，最后结合实例给出相应的仿真结果和分析。本文的仿真方法克服了传统编程语言仿真时繁杂、难度高、周期长的缺点。     

M序列BPSK引信信号的仿真建模与分析

为了考察M序列BPSK引信信号的特征,对M序列BPSK引信信号进行了仿真建模与分析;首先分析了M序列BPSK信号的数学模型以及M序列的数学模型,给出了一种M序列的计算机产生程序;然后应用SIKULINK做出了实际应用中的M序列产生器的仿真模型,并给出了仿真结果,再按照M序列BPSK脉冲信号的产生原理,使用SIMULINK仿真模型仿真得到引信中经常使用的127位M序列BPSK脉冲信号;最后,利用Matlab软件的作图功能,从自相关函数、频谱函数和模糊函数三个方面对M波形的性能进行了仿真分析.结果显示M序列BPSK信号有良好的扩谱效果,并揭示了M序列的阶数与信号各项性能的关系.     

The Delphi Method as a tool for information requirements specification

An application of the Delphi Method to the logical design of an Information System supporting the operation, control, evaluation and planning of student -related academic administration activities is presented. The logical design process was as follows: (1) a traditional top-down approach was used to define the system objectives and the information required to support structured (i.e., operational) activities; (2) the Delphi Method was used for generating a group opinion with respect to the proposed system objectives and the information required by unstructured and/or ill-structured decision making. The paper finally discusses how this search for group opinion significantly enhances the effectiveness of the resulting information system.     

The development of the Trefftzian methodology for engineering design analysis

This paper reviews the developments in the Trefftzian Methodology, which have been undertaken by the authors at the University of Sheffield during the past fifteen years and the application of these developments to engineering design analysis. Initially, in the late 1970s, this work concentrated on the Direct Boundary Element Method (DBEM) and the Indirect Boundary Element Method (IBEM). Unfortunately these methods, as they are normally formulated, give rise to singular integrals, which require special mathematical treatment, when the source and field points coincide on the boundary of the component being analysed. These singular integrals can however be eliminated by placing the source boundary outside the domain of the problem being analysed so that the field and source points never coincide. This technique is known as either the Regular Direct Boundary Element Method (RDBEM) or the Regular Indirect Boundary Element Method (RIBEM) In a further development of the RIBEM, based on the Trefftz Method, the continuous distribution of sources is replaced with sources distributed at discrete points on the source boundary. This modified Trefftz Method eliminates the integrations in the solution procedure, it provides a series solution in terms of the fundamental solution of the problem being analysed and is referred to as the Indirect Discrete Boundary Method (IDBM). The emergence of the IDBM provided the opportunity to develop a combined Boundary Element Finite Element technique which enables these methods to be used simultaneously in a single calculation, thereby exploiting their strengths and minimising their weaknesses. A number of case studies will be discussed in the paper to illustrate the developments in the Trefftzian Methodology and its application to engineering design analysis.     

基于MATLAB的伪随机序列的产生和分析

MATLAB由于其强大的功能而被广泛应用于很多工程领域。在扩频通信中通常的做法是用一扩频序列与信号相乘,从而得到频谱的扩展或压缩,因而扩频序列的性能直接决定着通信质量。伪随机序列中的m序列和Gold序列最常用作扩频序列。该文首先简单介绍了m序列和Gold序列的原理,性能和构造方法,接着在MATLAB中用M语言编程实现它们的产生和分析。仿真结果验证了该方法的正确性和可行性。该方法简练直观,适合工程技术人员参考。     

Web服务器区域访问流量预测模型设计

Web服务器上的日志文件记录了用户访问的许多有用的信息,分析和以它建立相应的预测模型,预测区域用户将来的访问行为,对提高Web服务器管理和服务质量,无疑是十分有价值的;Neuro-Fuzzy方法是将神经网络和模糊逻辑有机的结合,用于解决复杂的非线性问题;用它来进行Web服务器区域流量预测,是一种新的思路和方法。文章主要介绍了模型构造的基本思想、结构、算法,也介绍进化式聚类方法和预测过程;同时,给出了实验数据及分析。     

Implementation of spectral basis functions in BEM/FEM/GSM Domain Decomposition Methods devoted to scattering and radiation applications

In this paper, we discuss several improvements of a substructuring Domain Decomposition Method (DDM) devoted to Electromagnetic computations, based on the Boundary Element Method (BEM) and the Finite Element Method (FEM). This computation procedure is applied to the analysis of antenna performance on board vehicles as well as Radar Cross Section (RCS). The benefits of the subdomain Computational Electromagnetic Method are mainly the ability to deal with collaborative studies involving several companies, and the reduction of the computation costs by one or more orders of magnitude, especially in the context of parametric studies. Furthermore, this paper proposes a Spectral Basis Function (SBF) defined on fictitious surfaces surrounding equipment, to deal with both the computation of antenna far field patterns and RCS in a multi-domain mode. By masking the complexity of the equipment (wires, thin surfaces, materials, supply network, weapons) the external domain of the vehicle can be closed so that the Combined Field Integral Equation (CFIE) can be used, which is better conditioned than the Electric Field Integral Equation (EFIE). This calculation procedure leads to a faster convergence when using iterative Multi Level Fast Multiple Algorithms (MLFMA). The accuracy and efficiency of this technique is assessed by performing the computation of the diffraction and radiation of several test-objects in a multi-domain way cross compared with reference integral equation results.     

Task-oriented design of robot kinematics using the Grid Method

This paper presents a task-oriented design method for robot kinematics based on the Grid Method, which is widely used in the finite difference method and heat transfer/fluid flow analyses. This approach drastically reduces the complexity of the whole problem and increases the efficiency compared with previous approaches. More specifically, the Grid Method with a new formulation simplifies the design to a problem of a four-design-variable unit grid, which does not require solving inverse/forward kinematics. The efficiency of the Grid Method has been confirmed through a kinematics design of a planar robot for nuclear power plants and spatial robots.     

逆M序列在机抖激光陀螺消除动态闭锁中的应用

对逆M序列在消除激光陀螺动态闭锁误差中的应用进行了研究和验证.目前多采用M序列对抖动的幅度进行调制来消除激光陀螺动态闭锁误差,而逆M序列与M序列相比不仅满足注入到激光陀螺抖动中的要求,且比M序列有其性质等方面优势.通过理论分析及M序列和逆M序列在消除机抖激光陀螺动态闭锁中实验中的应用对比,实验数据表明逆M序列在消除动态闭锁中的作用要优于M序列.     

Numerical Simulation of Injection Molding Cooling Process Based on 3D Surface Model

The design of the cooling system of injection molds directly affects both productivity and the quality of the final part. Using the cooling process CAE system to instruct the mold design, the efficiency and quality of design can be improved greatly. At the same time, it is helpful to confirm the cooling system structure and optimize the process conditions. In this paper, the 3D surface model of mold cavity is used to replace the middle-plane model in the simulation by Boundary Element Metho…     

异构的动态分布式实时系统的面向方面的形式化方法

形式化方法是在严格的数学基础上建立的．具有精确数学含义的科学研究和验证方法。异构的动态分布式系统的开发过程是非常复杂的．不能用一种开发方法进行分析、设计和实现。由于形式化方法具有严谨、可数学分析和证明等特性,可以根据系统开发的不同方面采用不同的形式化语言进行实现．然后再把这些方面编织到系统中去。