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Stabilization for Singular Fractional-Order Systems via Static Output Feedback

IEEE ACCESS 2018年 6卷 71678-71684页

作者： Guo, Ying Lin, Chong Chen, Bing Wang, Qing-Guo Qingdao Univ Inst Complex Sci Qingdao 266071 Peoples R China Zaozhuang Univ Sch Math & Stat Zaozhuang 277160 Peoples R China Univ Johannesburg Fac Engn & Built Environm Inst Intelligent Syst Johannesburg South Africa

The stabilization problem of singular fractional-order systems with fractional commensurate order 0 < alpha < 2 via static output feedback is studied in this paper. For the 0 < alpha < 1 case, two methods for the static output feedback control design are provided. In the first method, the controller is designed without decomposing the system matrix, and less variables are within the second method. Furthermore, a method that is similar to the second method of the 0 < alpha < 1 case is provided for the 1 <= alpha < 2 case. The controller 6 parameters are computed by solving matrix inequalities, and efficient iterative algorithms are built to solve the resultant matrix inequalities. Numerical examples are provided to show the effectiveness of the proposed results.

关键词： Singular fractional-order systems linear matrix inequality (LMI) static output feedback iterative algorithm

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Transmission of an X-ray beam through a two-dimensional photonic crystal and the Talbot effect

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JOURNAL OF SYNCHROTRON RADIATION 2018年第2期25卷 425-431页

作者： Kohn, V. G. Natl Res Ctr Kurchatov Inst Kurchatov Sq 1 Moscow 123182 Russia

Results of computer simulations of the transmission of an X-ray beam through a two-dimensional photonic crystal as well as the propagation of an X-ray beam in free space behind the photonic crystal are reported. The photonic crystal consists of a square lattice of silicon cylinders of diameter 0.5 mm. The amount of matter in the path of the X-ray beam rapidly decreases at the sides of the cylinder projections. Therefore the transmission is localized near the boundaries, and appears like a channeling effect. The iterative method of computer simulations is applied. This method is similar to the multi-slice method that is widely used in electron microscopy. It allows a solution to be obtained with acceptable accuracy. A peculiarity in the intensity distribution inside the Talbot period z(T) in free space was found when the intensity is approximately equal to the initial value at a distance 0.46z(T), and it is shifted by half a period at distance 0.5z(T). The reason for this effect is the existence of a periodic phase of the wavefunction of radiation inside the intensity peaks. Simulations with zero phase do not show this effect. Symmetry rules for the Talbot effect are discussed.

关键词： X-ray transmission two-dimensional photonic crystal Talbot effect computer simulations iterative algorithm

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Multienergy element-resolved cone beam CT (MEER-CBCT) realized on a conventional CBCT platform

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MEDICAL PHYSICS 2018年第10期45卷 4461-4470页

作者： Shen, Chenyang Li, Bin Lou, Yifei Yang, Ming Zhou, Linghong Jia, Xun Univ Texas Southwestern Med Ctr Dallas Dept Radiat Oncol Dallas TX 75390 USA Sun Yat Sen Univ State Key Lab Oncol South China Ctr Canc Collaborat Innovat Ctr Canc Med Guangzhou 510060 Guangdong Peoples R China Univ Texas Dallas Dept Math Sci Dallas TX 75080 USA Southern Med Univ Dept Biomed Engn Guangzhou 510515 Guangdong Peoples R China

PurposeCone beam CT (CBCT) has been widely used in radiation therapy. However, its main application is still to acquire anatomical information for patient positioning. This study proposes a multienergy element-resolved (MEER) CBCT framework that employs energy-resolved data acquisition on a conventional CBCT platform and then simultaneously reconstructs images of x-ray attenuation coefficients, electron density relative to water (rED), and elemental composition (EC) to support advanced applications. MethodsThe MEER-CBCT framework is realized on a Varian TrueBeam CBCT platform using a kVp-switching scanning scheme. A simultaneous image reconstruction and elemental decomposition model is formulated as an optimization problem. The objective function uses a least square term to enforce fidelity between x-ray attenuation coefficients and projection measurements. Spatial regularization is introduced via sparsity under a tight wavelet-frame transform. Consistency is imposed among rED, EC, and attenuation coefficients and inherently serves as a regularization term along the energy direction. The EC is further constrained by a sparse combination of ECs in a dictionary containing tissues commonly existing in humans. The optimization problem is solved by a novel alternating-direction minimization scheme. The MEER-CBCT framework was tested in a simulation study using an NCAT phantom and an experimental study using a Gammex phantom. ResultsMEER-CBCT framework was successfully realized on a clinical Varian TrueBeam onboard CBCT platform with three energy channels of 80, 100, and 120kVp. In the simulation study, the attenuation coefficient image achieved a structural similarity index of 0.98, compared to 0.61 for the image reconstructed by the conventional conjugate gradient least square (CGLS) algorithm, primarily because of reduction in artifacts. In the experimental study, the attenuation image obtained a contrast-to-noise ratio 60, much higher than that of CGLS results (simila

关键词： cone beam CT dictionary elemental-resolved reconstruction iterative algorithm kVp-switching multi-energy

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Mim: A Merge Iteration and Its Applications for Big Data

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IEEE ACCESS 2018年 6卷 66984-66997页

作者： Song, Jie Wang, Han Zhang, Yichuan Bao, Yubing Yu, Ge Northeastern Univ Software Coll Shenyang 110819 Liaoning Peoples R China Northeastern Univ Sch Comp Sci & Engn Shenyang 110819 Liaoning Peoples R China

With the rapid development of technologies like the Internet, sensors and bioinformatics, and data has grown explosively. In the big data era, more and more iterative algorithms have been applied in the fields of data mining and machine learning. In most situation, the iterative algorithms compute in the entire dataset which are merged from the partial ones. Given the iterative results on partial datasets, it is efficient if the results on the entire dataset can be merged from them, otherwise the re-computing on entire one is time consuming. Unfortunately, current iteration model do not support the results merging. We propose merge iteration computing model (Mim) in this paper. Mim is a solution but not a platform. It states how to execute iterative algorithm effectively through reusing the exiting results without sacrificing the accuracy, and such mechanism is suitable for the most iterative algorithms. We explain the in-partition iteration step, error evaluation step, compensation step (optional), and merge iteration step of Mim, in addition, the in-partition iteration step is preliminary of merging iteration and should be done before the partial datasets are merged. We also analyze the accuracy and performance advantages of Mim theoretically. In the application scenarios, we implement Mim over Spark framework, and applied the Mim to the financial data analysis in a city. Finally, through a series of experiments, we prove the efficiency and accuracy of the proposed Mim on the PageRank and K-means algorithms. Under the various test cases, the maximum optimization ratio of Mim is 25% and 56% comparing with regular iteration on PageRank and K-means, respectively. And the errors are negligible.

关键词： Big data iterative computing model merge iteration iterative algorithm

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Adaptive Window-Based Constrained Energy Minimization for Detection of Newly Grown Tree Leaves

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REMOTE SENSING 2018年第1期10卷 96-96页

作者： Chen, Shih-Yu Lin, Chinsu Tai, Chia-Hui Chuang, Shang-Ju Natl Yunlin Univ Sci & Technol Dept Comp Sci & Informat Engn Touliu 64002 Yunlin Taiwan Natl Chiayi Univ Dept Forestry & Nat Resources Chiayi 60004 Taiwan

Leaf maturation from initiation to senescence is a phenological event of plants that results from the influences of temperature and water availability on physiological activities during a life cycle. Detection of newly grown leaves (NGL) is therefore useful for the diagnosis of tree growth, tree stress, and even climatic change. This paper applies Constrained Energy Minimization (CEM), which is a hyperspectral target detection technique to spot grown leaves in a UAV multispectral image. According to the proportion of NGL in different regions, this paper proposes three innovative CEM based detectors: Subset CEM, Sliding Window-based CEM (SW CEM), and Adaptive Sliding Window-based CEM (AWS CEM). AWS CEM can especially adjust the window size according to the proportion of NGL around the current pixel. The results show that AWS CEM improves the accuracy of NGL detection and also reduces the false alarm rate. In addition, the results of the supervised target detection depend on the appropriate signature. In this case, we propose the Optimal Signature Generation Process (OSGP) to extract the optimal signature. The experimental results illustrate that OSGP can effectively improve the stability and the detection rate.

关键词： hyperspectral detection target detection sprout detection constrained energy minimization iterative algorithm adaptive window

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H_∞ consensus for linear heterogeneous multi-agent systems with state and output feedback control

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NEUROCOMPUTING 2018年 275卷 2635-2644页

作者： Han, Ji Zhang, Huaguang Jiang, He Sun, Xun Northeastern Univ Coll Informat Sci & Engn Box 134 Shenyang 110819 Liaoning Peoples R China

In this paper, the problem of H-infinity consensus for linear heterogeneous multi-agent systems (HMASs) with state and output feedback control is investigated. By using the linear matrix inequality (LMI) theory, some basic properties of symmetric positive definite matrix and a series of analysis, the novel consensus conditions of using state and output feedback control and the corresponding algorithm are provided. The key idea of this paper is to convert one kind of nonlinear matrix inequality condition into a series of novel conditions that can be solved by using LMI toolbox and the most important characteristic of this paper is that the necessary and sufficient conditions of H-infinity consensus are provided while only sufficient conditions were given in some existing results. First, an equivalent condition for a special kind of nonlinear matrix inequality is given. Second, by using this equivalent condition, the necessary and sufficient conditions of H-infinity consensus for linear HMASs under state and output feedback control approaches are provided, respectively. Third, according to iterative algorithm and the property of trace of matrix, a feasible algorithm for calculating the controllers is proposed. Fourth, the obtained results are extended to solve the H-infinity control problem for general linear system with some additional conditions. At last, two numerical examples are given to support our results. (C) 2017 Elsevier B. V. All rights reserved.

关键词： H-infinity consensus Linear heterogeneous multi-agent system LMI theory State and output feedback iterative algorithm

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Recursive and iterative Least Squares Parameter Estimation algorithms for Multiple-Input-Output-Error Systems with Autoregressive Noise

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CIRCUITS SYSTEMS AND SIGNAL PROCESSING 2018年第5期37卷 1884-1906页

作者： Ding, Jiling Jining Univ Dept Math Qufu 273155 Peoples R China Jiangnan Univ Sch Internet Things Engn Wuxi 214122 Peoples R China

This paper considers the parameter estimation of a multiple-input-output-error system with autoregressive noise. In order to solve the problem of the information vector containing unknown inner variables, an auxiliary model-based recursive generalized least squares algorithm and a least squares-based iterative algorithm are proposed according to the auxiliary model identification idea and the iterative search principle. The simulation results indicate that the least squares-based iterative algorithm can generate more accurate parameter estimates than the auxiliary model-based recursive generalized least squares algorithm. Two examples are given to test the proposed algorithms.

关键词： iterative algorithm Parameter estimation Least squares Multivariable system Auxiliary model

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Gradient-based iterative parameter estimation for bilinear-in-parameter systems using the model decomposition technique

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IET CONTROL THEORY AND APPLICATIONS 2018年第17期12卷 2380-2389页

作者： Chen, Mengting Ding, Feng Yang, Erfu Jiangnan Univ Lab Adv Proc Control Light Ind Minist Educ Sch Internet Things Engn Wuxi 214122 Peoples R China Qingdao Univ Sci & Technol Coll Automat & Elect Engn Qingdao 266061 Peoples R China Univ Strathclyde Space Mechatron Syst Technol Lab Glasgow G1 1XJ Lanark Scotland

The parameter estimation issues of a block-oriented non-linear system that is bilinear in the parameters are studied, i.e. the bilinear-in-parameter system. Using the model decomposition technique, the bilinear-in-parameter model is decomposed into two fictitious submodels: one containing the unknown parameters in the non-linear block and the other containing the unknown parameters in the linear dynamic one and the noise model. Then a gradient-based iterative algorithm is proposed to estimate all the unknown parameters by formulating and minimising two criterion functions. The stochastic gradient algorithms are provided for comparison. The simulation results indicate that the proposed iterative algorithm can give higher parameter estimation accuracy than the stochastic gradient algorithms.

关键词： parameter estimation gradient methods nonlinear control systems bilinear systems stochastic gradient algorithms iterative algorithm bilinear-in-parameter system model decomposition technique parameter estimation issues block-oriented nonlinear system bilinear-in-parameter model nonlinear block noise model gradient-based iterative parameter estimation

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Guaranteed cost control of periodic piecewise linear time-delay systems

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AUTOMATICA 2018年 94卷 274-282页

作者： Xie, Xiaochen Lam, James Univ Hong Kong Dept Mech Engn Pokfulam Hong Kong Peoples R China

This paper is concerned with the guaranteed cost control problem for continuous-time periodic piecewise linear systems with time delay. Sufficient delay-dependent conditions of closed-loop asymptotic stability are presented based on an improved formulation, which uses a novel Lyapunov-Krasovskii functional with relaxed requirement in positive definiteness of the involved symmetric matrices. The corresponding optimization problems aiming at the mixed performance involving an upper bound of H-2 guaranteed cost and an H-infinity performance index for disturbance attenuation are established. By designing an iterative algorithm subject to the proposed conditions, the periodic guaranteed cost controller gains over each sub-interval are tractable for the resulting closed-loop time-delay system. The effectiveness and reduced conservatism of our proposed criteria are validated and illustrated via numerical simulations. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Guaranteed cost control H-infinity performance iterative algorithm Periodic piecewise systems Time delay

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Methods for estimating hysteretic behavior and vibration responses of a timing belt tensioner

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ADVANCES IN MECHANICAL ENGINEERING 2019年第11期11卷

作者： Long, Shangbin Yin, Zhihong Zhao, Xuezhi Shangguan, Wen-Bin South China Univ Technol Sch Mech & Automot Engn Wushan Rd Guangzhou 510641 Guangdong Peoples R China

An automatic tensioner that consists of a torsional spring and friction damping elements is widely used in belt drive system. The relation of the applied torque versus the imposed angle of tensioner during loading and unloading processes is described as a hysteretic loop. An analytical model is established for estimating the hysteretic behavior of a tensioner, and measurements for hysteretic loop in quasi-static and dynamic excitation are carried out to validate the analytical model. Taking one engine timing belt drive system as a studying example, the method and the procedure for estimating vibration responses of the nonlinear tensioner are given. An iterative algorithm for predicting the accurate equivalent viscous damping of tensioner is carried out in analyzing a belt drive system. The vibration responses of tensioner are validated by the measurement of timing belt drive system. The developed method presented in this article is useful for predicting the hysteretic behavior of tensioner, vibration responses, and the parameters optimization of a belt drive system.

关键词： Nonlinear tensioner hysteretic behavior analytical model iterative algorithm vibration responses

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