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61.
This paper investigates robust observer‐controller compensator design using Vidyasagar's structure (VS). VS has a unit matrix parameter H similar to the Q parameter for the Youla–Kucera parameterization. VS can be designed based on the left coprimeness of the central controller in the H∞‐loop shaping design procedure (H∞‐LSDP) and therefore can preserve the intrinsic properties of the H∞‐LSDP. This paper introduces algebraic methods to simplify the design of H in the VS controller by solving specific algebraic equations. In particular, the algebraic design of H can achieve two things. First, a dynamic H adjusts the tracking performance and yields the integral action. Second, a dynamic H rejects the input and output sinusoidal disturbances with known frequencies. These attributes are indications of the flexibility of the proposed method since the output‐feedback controller design of the H∞‐LSDP cannot easily deal with such conditions. This paper discusses the achieved loop and the closed‐loop behavior of the system with VS, and also gives two numerical examples. The first example shows that the proposed method results in a better design in many aspects than the resulting from H∞‐LSDP. The second example shows the application of the proposed method to rejecting input and output step disturbances, and input and output multiple sinusoidal disturbances, for which the H∞‐LSDP can hardly be used. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
62.
Guangsheng Chi Gongsheng Li Xianzheng Jia 《Computers & Mathematics with Applications》2011,62(4):1619-1626
This paper deals with an inverse problem of determining a source term in the one-dimensional fractional advection-dispersion equation (FADE) with a Dirichlet boundary condition on a finite domain, using final observations. On the basis of the shifted Grünwald formula, a finite difference scheme for the forward problem of the FADE is given, by means of which the source magnitude depending upon the space variable is reconstructed numerically by applying an optimal perturbation regularization algorithm. Numerical inversions with noisy data are carried out for the unknowns taking three functional forms: polynomials, trigonometric functions and index functions. The reconstruction results show that the inversion algorithm is efficient for the inverse problem of determining source terms in a FADE, and the algorithm is also stable for additional data having random noises. 相似文献
63.
为了解决传统基于GBB方法的正则化二值图像复原算法放大背景噪声的问题,提出了一种基于GBB方法的改进的正则化二值图像复原算法。根据提出的算法进行实验,定性的对两种算法的图像复原结果进行了比较。同时,利用ISNR选取最佳参数,且在不同程度噪声的影响下定量的评价了两种复原方法的结果。实验结果表明,该方法对于模糊二值图像的复原效果有显著提升,有效降低了噪声对图像复原的影响。 相似文献
64.
The geometric element transformation method (GETMe) is a geometry-based smoothing method for mixed and non-mixed meshes. It
is based on a simple geometric transformation applicable to elements bounded by polygons with an arbitrary number of nodes.
The transformation, if applied iteratively, leads to a regularization of the polygons. Global mesh smoothing is accomplished
by averaging the new node positions obtained by local element transformations. Thereby, the choice of transformation parameters
as well as averaging weights can be based on the element quality which leads to high quality results. In this paper, a concept
of an enhanced transformation approach is presented and a proof for the regularizing effect of the transformation based on
eigenpolygons is given. Numerical examples confirm that the GETMe approach leads to superior mesh quality if compared to other
geometry-based methods. In terms of quality it can even compete with optimization-based techniques, despite being conceptually
significantly simpler. 相似文献
65.
In this study, we are concerned with system modeling which involves limited data and reconciles the developed model with some previously acquired domain knowledge being captured in the format of already constructed models. Each of these previously available models was formed on a basis of extensive data sets which are not available for the current identification pursuits. To emphasize the nature of modeling being guided by the reconciliation mechanisms, we refer to this mode of identification as experience-consistent modeling. The paper presents the conceptual and algorithmic framework by focusing on regression models. By forming a certain extended form of the performance index, it is shown that the domain knowledge captured by regression models can play a similar role as a regularization component used quite commonly in system identification. Experimental results involve both synthetic low-dimensional data and selected data coming from Machine Learning repository. The data used in the experiments tackle regression models as well as classification problems (two-class classifiers). 相似文献
66.
Jean-François Aujol 《Journal of Mathematical Imaging and Vision》2009,34(3):307-327
This paper deals with first-order numerical schemes for image restoration. These schemes rely on a duality-based algorithm proposed in 1979 by Bermùdez and Moreno. This is an old and forgotten algorithm that is revealed wider than recent schemes (such as the Chambolle projection algorithm) and able to improve contemporary schemes. Total variation regularization and smoothed total variation regularization are investigated. Algorithms are presented for such regularizations in image restoration. We prove the convergence of all the proposed schemes. We illustrate our study with numerous numerical examples. We make some comparisons with a class of efficient algorithms (proved to be optimal among first-order numerical schemes) recently introduced by Y. Nesterov. 相似文献
67.
建立其交流异步电机的欧拉—拉格朗日数学模型,再以无源控制理论实现电机调速控制。为了转速反馈的准确性,加入了转速估算环节。充分利用被控系统已有的结构,直接比较给定的电磁转矩和估算的电磁转矩,运用PI闭环控制构造出转速信号。在Simulink中搭建仿真模型进行实验,仿真结果表明:此控制方法对交流异步电机速度控制具有较好的静/动态性能和抗干扰性。 相似文献
68.
69.
70.
Matthew O.T. ColeAuthor vitae 《Automatica》2011,47(11):2504-2510
Modifying a command or actuation signal by convolving it with a sequence of impulses is a useful technique for eliminating structural vibration in rest-to-rest motion of mechanical systems. This paper describes an adaptive discrete-time version of this approach where amplitude and timing of impulses are tuned during operation to match the system under control. Solutions giving zero residual vibration are formulated in terms of a quadratic cost function and constructed by iterative operations on measured sets of input–output data. The versatility of the approach is demonstrated by simulated test cases involving (1) amplitude optimization of impulses with fixed timings, (2) timing optimization of impulses with fixed amplitudes and (3) combined timing and amplitude optimization. The approach is model-free and directly applicable to multi-mode systems. Moreover, fast adaptation within a single rest-to-rest maneuver can be achieved. 相似文献