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A nonlinear adaptive sliding mode control strategy for modular high-temperature gas-cooled reactors

PROGRESS IN NUCLEAR ENERGY 2019年 113卷 53-61页

作者： Wang, Guoxu Wu, Jie Zeng, Bifan Xu, Zhibin Ma, Xiaoqian South China Univ Technol Sch Elect Power 381 Wu Shan Rd Guangzhou 510640 Guangdong Peoples R China Guangdong Prov Key Lab Efficient & Clean Energy U Guangzhou 510640 Guangdong Peoples R China Shunde Inspect Inst Special Equipment Inspect & Res Inst Guangdong Pr Shunde 528300 Peoples R China Guangdong Power Grid Corp Elect Power Res Inst Guangzhou 510080 Guangdong Peoples R China

Modular high-temperature gas-cooled nuclear reactor (MHTGR) has attracted comprehensive attention for its reliable inherent safety, and an effective control strategy is needed to control the output power of the MHTGRs at desired levels. This paper aims to develop a nonlinear power-level tracking controller based on sliding mode control (SMC) strategy for the MHTGRs. By introducing Takagi-Sugeno (TS) fuzzy system for nonlinear modeling, the MHTGR model is represented by TS models. The control law is designed based on the TS models and the sliding mode surface that is defined as the tracking error, and an adaptive algorithm is also included in the proposed control law to reduce the chattering phenomenon of SMC. In addition, the stability of the closed-loop control system is also guaranteed by the proposed control law. To evaluate the performance of the proposed nonlinear adaptive sliding mode control (NASMC) strategy, a traditional nonlinear sliding mode control (TNSMC) strategy and a Proportional-Integral-Derivative (PID) control strategy are presented for comparison. Simulation results show the effectiveness and the advantages of the proposed NASMC strategy, and most importantly, the proposed NASMC strategy does not suffer from chattering.

关键词： Takagi-Sugeno fuzzy system Sliding mode control adaptive algorithm Modular high-temperature gas-cooled nuclear reactor Power level control

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Optimal adaptivity for the SUPG finite element method

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COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2019年第Aug.15期353卷 308-327页

作者： Erath, Christoph Praetorius, Dirk Tech Univ Darmstadt Darmstadt Germany TU Wien Vienna Austria

For convection dominated problems, the streamline upwind Petrov-Galerkin method (SUPG), also named streamline diffusion finite element method (SDFEM), ensures a stable finite element solution even on coarse meshes, i.e., in the preasymptotic range. Based on some a posteriori error estimators from the literature, we formulate an adaptive mesh-refining algorithm for SUPG. We prove that the adaptively generated SUPG solutions converge at asymptotically optimal rates towards the exact solution. The main focus thus is on the mathematical proof that the SUPG stabilization does not spoil the asymptotic convergence behavior of the adaptive scheme. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Streamline Upwind Petrov-Galerkin method (SUPG) Streamline diffusion finite element method (SDFEM) a posteriori error estimate adaptive algorithm Local mesh-refinement Optimal convergence rates

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Effective finite element model in-loop system of laminated cylindrical structure for multiple inputs and multiple outputs active vibration control

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JOURNAL OF LOW FREQUENCY NOISE VIBRATION AND ACTIVE CONTROL 2019年第2期38卷 664-683页

作者： Liu, Jinxin Cui, Minqi Qiao, Baijie Li, Zengguang Yang, Zhibo Chen, Xuefeng Xi An Jiao Tong Univ State Key Lab Mfg Syst Engn Xian Shaanxi Peoples R China Xi An Jiao Tong Univ Sch Mech Engn Xian Shaanxi Peoples R China China Ship Dev & Design Ctr Shanghai Peoples R China

Active vibration control of large laminated cylindrical structures, for example, the cabin of space, air, surficial or subaqueous vehicles, usually requires multiple inputs and multiple outputs to the system, since there are usually multiple vibration sources and each source contains multiple frequency components. The performance of multiple inputs and multiple outputs control system will be dramatically affected by the complex dynamic behavior of the laminated cylindrical structure, thus an effective model is in great request in analyzing and designing the control system. However, there is seldom distributed parametric model, typically, finite element model, applying to the active vibration control system, because of its computational complexity. In this work, we propose an effective finite element model in-loop system of laminated cylindrical structure for multiple inputs and multiple outputs active vibration control simulation. Firstly, an finite element model of laminated thick cylindrical structure with four-node Mindlin degenerated shell element has been constructed. Then, a model reduction procedure has been proposed to obtain in-loop model of the control system. The numerical global modal analysis and harmonic response analysis of the cylindrical structure have been conducted to verify the correctness of the model. Afterward, a multiple inputs and multiple outputs adaptive algorithm which is able to coup with multiple frequencies and multiple sources vibration has been applied to the finite element model in-loop system. Finally, four numerical case studies have been conducted, in which the vibration sources contain multiple frequency components and artificial colored noises. The result shows that the vibration of the multiple control points can be dramatically suppressed simultaneously, which demonstrates the effectiveness of the algorithm and finite element model in-loop system.

关键词： Active vibration control multiple inputs and multiple outputs finite element model in-loop system adaptive algorithm

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A Short Survey on adaptive algorithms in Identifying Wiener Models 3

A Short Survey on Adaptive Algorithms in Identifying Wiener ...

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3rd International Conference on Information Technology Research (ICITR)

作者： Yang, Chan-Yun Yang, Jr-Syu Yu, Liyu Natl Taipei Univ Dept Elect Engn New Taipei Taiwan Tamkang Univ Dept Mech & Electromech Engn New Taipei Taiwan

ISBN: (纸本)9781728114705

Wiener model with its corresponding excellence were often adopted to identify varieties of nonlinear systems. The short paper is aimed to explore the rationale to establish the model from its very theoretical beginning. To uncover the success of the model, the key of the adaptive algorithms which are capable of adapting the changes of the dynamics is also covered.

关键词： nonlinear system identification Wiener model adaptive algorithm

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An adaptive Unsupervised Learning Framework for Monocular Depth Estimation

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IEEE ACCESS 2019年 7卷 148142-148151页

作者： Yang, Delong Zhong, Xunyu Lin, Lixiong Peng, Xiafu Xiamen Univ Dept Automat Xiamen 361005 Peoples R China Fuzhou Univ Sch Mech Engn & Automat Fuzhou 350116 Peoples R China

Depth estimation from a single image plays an important role in 3D scene perception. Owing to the development of deep convolutional neural networks (CNNs), monocular depth estimation models have achieved a large number of exciting results. However, the requirement for the manual per-pixel labeled dataset (ground truth) limits the application of these supervised methods. Basing on a geometric constraint between the consecutive stereo images, we propose an unsupervised method to infer the scene structure. We train the model with consecutive stereo images as input while only a single image is required at test time. In contrast to previous works, this paper presents an adaptive loss function to tackle the regions which are non-overlapping between consecutive images. Moreover, by exploiting the pixels' discontinuity in the edge region and the continuity in the non-edge region of a depth image, we propose a novel depth smoothness loss to improve the accuracy of the model. In addition, as an auxiliary task, our model also obtains the camera motion between consecutive images. Experimental results on the KITTI and Cityscapes datasets show that our model outperforms other unsupervised frameworks and some supervised frameworks.

关键词： Neural networks unsupervised learning image sequences image processing monocular depth estimation adaptive algorithm

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A new hybrid adaptive combination technique for ECG signal enhancement

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MULTIDIMENSIONAL SYSTEMS AND SIGNAL PROCESSING 2019年第3期30卷 1309-1325页

作者： Althahab, Awwab Qasim Jumaah Univ Babylon Coll Engn Dept Elect Engn Babil Iraq

This paper proposes a new de-noising system technique which is composed of adaptive line enhancer (ALE) with the discrete wavelet transform (DWT) in order to improve the demerit of the ALE. A new adaptive algorithm which depends mainly on the second order resemblance between a signal and its delayed version is also derived and proposed for the ALE. Unlike the conventional DWT process where an estimation of a specific threshold is taken into account, here the ALE based proposed adaptive algorithm is exploited to enhance the detail coefficients. Therefore, the entire system works well for canceling Gaussian and non-Gaussian noise. Some experiments are carried out on an ECG signal to show the effectiveness of the proposed system. It illustrates from the simulations that the proposed technique demonstrates spectacular results for separating various noise types from the contaminated ECG signal. Finally, the proposed adaptive algorithm is compared with the leaky least mean square algorithm of the bases of mean square error. It is found that the performance of the proposed algorithm provides faster convergence rate and lower steady-state error. Consequently, the overall proposed system model represents a workable solution for ECG signal enhancement.

关键词： Electrocardiogram De-noising adaptive line enhancer adaptive algorithm DWT and L-LMS

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adaptive online dictionary learning for bearing fault diagnosis

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2019年第1-4期101卷 195-202页

作者： Lu, Yanfei Xie, Rui Liang, Steven Y. Georgia Inst Technol George W Woodruff Sch Mech Engn Atlanta GA 30332 USA Univ Georgia Dept Stat Athens GA 30602 USA Donghua Univ Coll Mech Engn Shanghai 201620 Peoples R China

One of the most common parts to maintain system balance and support the various load in rotating machinery is the rolling element bearing. The breakdown of the element in bearings leads to inefficiency and sometimes catastrophic events across various industries. The main challenge over the last few years for fault diagnosis of bearings is the early detection of fault signature. In this paper, an adaptive online dictionary learning algorithm is developed for early fault detection of bearing elements. The dictionary is trained using a set of vibration signal from a heavily damaged bearing. The enveloped signal of the bearing is obtained using the Kurtogram and split into several sections. The K-SVD algorithm is implemented to the dictionaries corresponding to the enveloped signal. OMP is implemented with the calculated dictionaries to obtain the sparse representation of the testing signal. Then the envelope analysis is implemented to obtain the fault signal from the recovered signal by the dictionaries. The adaptive algorithm is added to the dictionary learning to update the dictionary based on newly acquired data with the weighted least square method. Without retraining the dictionaries using the K-SVD algorithm, the computation speed is significantly improved. The proposed algorithm is compared with a traditional dictionary learning algorithm to show the improvement in detection of new fault frequency and improved signal to noise ratio.

关键词： Ball bearing Fault diagnosis Dictionary learning adaptive algorithm

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Nonlinear Differential Equation Solvers via adaptive Picard-Chebyshev Iteration: Applications in Astrodynamics

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JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 2019年第5期42卷 1007-1022页

作者： Woollands, Robyn Junkins, John L. Texas A&M Univ Dept Aerosp Engn College Stn TX 77843 USA

An adaptive self-tuning Picard-Chebyshev numerical integration method is presented for solving initial and boundary value problems by considering high-fidelity perturbed two-body dynamics. The current adaptation technique is self-tuning and adjusts the size of the time interval segments and the number of nodes per segment automatically to achieve near-maximum efficiency. The technique also uses recent insights on local force approximations and adaptive force models that take advantage of the fixed-point nature of the Picard iteration. In addition to developing the adaptive method, an integral quasi-linearization "error feedback" term is introduced that accelerates convergence to a machine precision solution by about a of two. The integral quasi linearization can be implemented for both first- and second-order systems of ordinary differential equations. A discussion is presented regarding the subtle but significant distinction between integral quasi linearization for first-order systems, second-order systems that can be rearranged and integrated in first-order form, and second-order systems that are integrated using a kinematically consistent Picard-Chebyshev iteration in cascade form. The enhanced performance of the current algorithm is demonstrated by solving an important problem in astrodynamics: the perturbed two-body problem for near-Earth orbits. The adaptive algorithm has proven to be more efficient than an eighth-order Gauss-Jackson and a 12th/10th-order Runge-Kutta while maintaining machine precision over several weeks of propagation.

关键词： Second Order Differential Equations Eccentric Anomaly Predictor Corrector Method Earth Boundary Value Problems adaptive algorithm Self Tuning Geostationary Transfer Orbit Perigee Computing

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A posteriori error analysis for the scattering by obstacles in a homogeneous chiral environment

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APPLIED NUMERICAL MATHEMATICS 2019年 135卷 246-263页

作者： Wang, Zhoufeng Guo, Rui Henan Univ Sci & Technol Sch Math & Stat Luoyang 471023 Henan Peoples R China Shihezi Univ Coll Sci Xinjiang 832003 Peoples R China

In this paper we consider the scattering of time-harmonic electromagnetic wave propagation in a homogeneous chiral environment by obstacles. The model is simplified to a two-dimensional scattering problem, and is formulated as a boundary value problem in a bounded domain by introducing the nonlocal boundary conditions associated with Dirichlet-to-Neumann operators. An a posteriori error estimate is established when the truncation of the nonlocal boundary operators takes place. The crucial part of the error analysis is to develop a duality argument and use the Bohren decomposition of the electromagnetic fields. The a posteriori error estimate consists of two parts, finite element approximation error and the truncation error of boundary operators which decays exponentially with respect to the truncation parameter. Numerical experiments are also presented to show the robustness and effectiveness of our numerical algorithm. (C) 2018 IMACS. Published by Elsevier B.V. All rights reserved.

关键词： Maxwell's equations Scattering A posteriori error analysis adaptive algorithm

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An adaptive Cascaded ILA- and DLA-Based Digital Predistorter for Linearizing an RF Power Amplifier

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2019年第3期66卷 1031-1041页

作者： Le Duc, Han Feuvrie, Bruno Pastore, Matthieu Wang, Yide Univ Nantes UMR CNRS 6164 Inst Elect & Telecommun Rennes F-44035 Nantes France Telerad Co F-64603 Anglet France

This paper presents a novel adaptive digital predistortion (DPD) technique based on a cascade of an adaptive indirect learning architecture (ILA) and a static direct learning architecture (DLA) using a linear interpolation look-up-table (LILUT). The static LILUT-DLA-based DPD is designed to identify the inverse of a radio-frequency power amplifier (PA) model. The cascaded system of the DLA-based predistorter (PD) and PA is theoretically linear. However, in real-time applications, the PA characteristics change with time due to process, supply voltage, and temperature variations, making this cascaded system not strictly linear, which results in some residual nonlinear distortion at the PA output. This residual distortion is effectively compensated by an additional adaptive HA-based PD using least mean squares or recursive least squares. Thanks to the incorporation of the static DLA, the proposed DPD approach is less sensitive to the PA output noise, ensuring a better preinverse of the PA and also requiring a smaller number of adaptive coefficients than either the adaptive stand-alone DLA- or ILA-based DPDs. The experimental results show that the proposed DPD technique effectively linearizes the PA, even if its characteristics change, and obtains better linearization performance than either the classical stand-alone DLA- or stand-alone ILA-based DPDs.

关键词： Nonlinear systems power amplifier adaptive digital predistortion (DPD) indirect learning architecture (ILA) direct learning architecture (DLA) adaptive algorithm

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