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arXiv 2017年

作者： Ouyang, Bin Xiong, Shiyun Yang, Zhi Jing, Yuhang Wang, Yongjie National Center for Supercomputing Applications University of Illinois at Urbana-Champaign UrbanaIL61801 United States Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow University Suzhou JiangSu215123 China College of Physics and Optoelectronics Taiyuan University of Technology Taiyuan ShanXi030024 China Key Lab of Advanced Transducers and Intelligent Control System Ministry of Education and Shanxi Province Taiyuan University of Technology Taiyuan ShanXi030024 China Department of Astronautical Science and Mechanics Harbin Institute of Technology Harbin Heilongjiang150001 China Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign UrbanaIL61801 United States Department of Electrical Engineering and Computer Engineering University of Michigan Ann ArborMI48109 United States

Due to the distinguished properties offered by different structural phases of monolayer MoS2, phase engineering design are urgently required for achieving switchable structural phase. Strain engineering is widely accepted as a clean and flexible method, however, can not be achieved in engineering monolayer MoS2 phase transition because the critical biaxial strain required (~15%) is much larger than measured elastic limit (~11%). In this study, employing density functional theoretical calculations, it has been found out that with the forming of heterostructure between MoS2 with buckled 2D materials such as silicence, germanene and stanene, only a small strain can trigger the phase transition. As being suggested by the constructed phase stability diagram, biaxial deformation as low as 3% in MoS2/silicene and MoS2/stanene sandwich structure, would be sufficient to induce the structural phase transition in MoS2 lattice. This strain falls well within experimental elastic limit, thus would be feasible to realize in experiment. The origin of such behavior can be understood as strain induced interlayer covalent bond formation, which finally make MoS2 lattice more sensitive to external strain. This theoretical work provides one realistic route for achieving flexible phase stabilities in experimental design. Copyright © 2017, The Authors. All rights reserved.

关键词： Molybdenum compounds

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Constructions of Lyapunov Functions for Large-scale Networked control systems with Packet-based Communication

Constructions of Lyapunov Functions for Large-scale Networke...

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European control Conference

作者： W.P.M.H. Heemels D.P. Borgers V.S. Dolk R. Geiselhart S.H.J. Heijmans the Control System Technology Group Department of Mechanical Engineering Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands the Faculty of Computer Science and Mathematics of the University of Passau Innstrasse 33 94032 Passau Germany

ISBN: (纸本)9781509025923

In this tutorial presentation we focus on the construction of Lyapunov or storage functions for large-scale networked control systems (NCSs) in which sensors, controllers and actuators are connected via multiple (local) communication networks which operate asynchronously and independently of each other. Within each packet-based communication network only one node can communicate at a given transmission time (requiring communication protocols) and the transmission intervals and delays may vary over time. These artefacts cause network-induced communication errors in the overal closed-loop system and can be detrimental for stability and performance. For these NCSs we provide explicit constructions of Lyapunov functions by modelling the large-scale NCS as an interconnection of a finite or even an infinite number of hybrid subsystems, and combining 'local' Lyapunov functions for the controlled dynamics (including network-induced errors) and the protocols in a systematic manner. These constructions lead to the numerical computation of maximum allowable transmission intervals (MATIs) and maximum allowable delays (MADs) for each of the individual networks. The availability of the Lyapunov or storage functions guarantee properties such as global asymptotic or exponential stability, input-to-state stability (ISS) and, L_p-stability for the large-scale NCS. Interestingly, the control performance expressed in terms of ISS and L_p-gains can be traded with the network parameters (MATIs and MADs). Hence, tradeoffs can be made between the quality-of-control of the overal hybrid system and the required quality-of-service of the underlying communication infrastructure. Also event-triggered communication schemes will be shortly discussed. The results are illustrated with an example of vehicle platooning.

关键词： NCSs Constructions Lyapunov Functions

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An Adaptive Model Selection Strategy for Surrogate-Assisted Particle Swarm Optimization Algorithm

An Adaptive Model Selection Strategy for Surrogate-Assisted ...

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IEEE Symposium Series on Computational Intelligence

作者： Haibo Yu Chaoli Sun Yin Tan Jianchao Zeng Yaochu Jin School of Mechanical Engineering Taiyuan University of Science and Technology Taiyuan 030024 China Department of Computer Science and Technology Taiyuan University of Science and Technology Taiyuan 030024 China Division of Industrial and System Engineering Taiyuan University of Science and Technology Taiyuan 030024 China School of Computer Science and Control Engineering North University of China Taiyuan 030051 China Department of Computer Science University of Surrey Guildford GU2 7XH UK

ISBN: (纸本)9781509042418

Computationally expensive problems pose a serious challenge to the successful application of evolutionary algorithms to complex engineering optimization. To address this challenge, surrogate models, also known as metamodels, are commonly used in lieu of the expensive fitness function for the computational cost of optimization. However, it is nontrivial to choose an appropriate metamodel for properly replacing the expensive fitness function. In this paper, an adaptive model selection strategy based on fitness landscape analysis is proposed for a surrogate-assisted particle swarm optimization algorithm. The structure of the sampling space is learned, based on which the more suited surrogate model, either a polynomial regression model or a radial basis function network, will be chosen to estimate the fitness value. Simulation results on seven widely used benchmark functions demonstrate the efficacy of the proposed algorithm.

关键词： Surrogate models Particle swarm optimization Fitness landscape analysis Fitness distance correlation Model selection

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A Two-Step Fault Diagnosis Framework for Rolling Element Bearings with Imbalanced Data

A Two-Step Fault Diagnosis Framework for Rolling Element Bea...

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International Conference on Ubiquitous Robots and Ambient Intelligence

作者： Yuan Lan Weiwei Zong Xiaojian Ding Xiaoyan Xiong Xiaohang Han Jiahai Huang Bing Ma Key Laboratory of Ministry of Education in Advance Transducers and Intelligent Control System Institute of Mechatronics Engineering under School of Mechanical Engineering Taiyuan University of Technology Department of Computer Science Wayne State University Science and Technology on Information Systems Engineering Laboratory The Second Research Institute of China Electronic Technology Group Corporation

ISBN: (纸本)9781509008223

Rolling element bearings constitute the key parts on rotating machinery and their fault diagnosis are of great importance. In this paper, a novel Two-Step fault diagnosis framework is proposed to diagnose the status of rolling element bearings with imbalanced data. The Wavelet Packet Transform (WPT) is used to determine the feature vectors. 16-dimensional wavelet packet node energies were extracted from the original datasets as the feature vectors prepared to input to the classifiers. Next, our proposed framework consists of two steps for the fault diagnosis, where Step One makes use of Weighted Extreme Learning Machine (weighted ELM) in an effort to classify the normal or abnormal categories, and Step Two further diagnoses the underlying anomaly in details. The effectiveness of our proposed approach is testified on the raw data collected from the rolling element bearing experiments conducted in our Institute, and the empirical results showed that our approach is really fast and can achieve the diagnosis accuracies more than 95%.

关键词： Two-Step fault diagnosis framework Weighed ELM ELM Bearing fault diagnosis

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A Two-Step Fault Diagnosis Framework for Rolling Element Bearings with Imbalanced Data

A Two-Step Fault Diagnosis Framework for Rolling Element Bea...

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2016 13th International Conference on Ubiquitous Robots and Ambient Intelligence (URAI)

作者： Yuan Lan Weiwei Zong Xiaojian Ding Xiaoyan Xiong Xiaohang Han Jiahai Huang Bing Ma Key Laboratory of Ministry of Education in Advance Transducers and Intelligent Control System Institute of Mechatronics Engineering under School of Mechanical EngineeringTaiyuan University of Technology Department of Computer Science Wayne State University Science and Technology on Information Systems Engineering Laboratory The Second Research Institute of China Electronic Technology Group Corporation

Rolling element bearings constitute the key parts on rotating machinery and their fault diagnosis are of great importance. In this paper, a novel Two-Step fault diagnosis framework is proposed to diagnose the status of rolling element bearings with imbalanced data. The Wavelet Packet Transform(WPT) is used to determine the feature vectors. 16-dimensional wavelet packet node energies were extracted from the original datasets as the feature vectors prepared to input to the ***, our proposed framework consists of two steps for the fault diagnosis, where Step One makes use of Weighted Extreme Learning Machine(weighted ELM) in an effort to classify the normal or abnormal categories, and Step Two further diagnoses the underlying anomaly in details. The effectiveness of our proposed approach is testified on the raw data collected from the rolling element bearing experiments conducted in our Institute,and the empirical results showed that our approach is really fast and can achieve the diagnosis accuracies more than 95%.

关键词： Two-Step fault diagnosis framework Weighed ELM ELM Bearing fault diagnosis

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Coordination of power injection in HVDC grids with multi-TSOs and large wind penetration 11

Coordination of power injection in HVDC grids with multi-TSO...

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11th IET International Conference on AC and DC Power Transmission

作者： Babazadeh, Davood Van Hertem, Dirk Rabbat, Michael Nordström, Lars Industrial Information and Control System Department School of Electrical Engineering KTH-Royal Institute of Technology Sweden Esat-Electa KU Leuven Belgium Department of Electrical and Computer Engineering McGill University Canada

ISBN: (纸本)9781849199827

This paper proposes different architectures for the coordination of power injection in interconnected hybrid AC/DC grids with Multi-TSO. The power dispatch problem is first formulated for the HVDC grid with the aim of keeping the balance in real time and try to follow the 15-min schedules introduced by AC TSOs considering the ongoing changes in the HVDC grid. Next, the Auxiliary Problem Principle (APP) method is proposed to decompose the dispatch problem and distributed between connected AC operators who control the local converters. Two different approaches are tested and the sensitivity of the OPF updating rate has been evaluated for a 5-area HVDC grid with the wind production.

关键词： Electric load flow

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A Generalized Piecewise Quadratic Lyapunov Function Approach to Estimating the Domain of Attraction of a Saturated system

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IFAC-PapersOnLine 2015年第11 11期48卷 120-125页

作者： Li, Yuanlong Lin, Zongli Department of Automation Shanghai Jiao Tong University Key Laboratory of System Control and Information Processing of Ministry of Education Shanghai200240 China Charles L. Brown Department of Electrical and Computer Engineering University of Virginia CharlottesvilleVA22904-4743 United States

This paper revisits the problem of estimating the domain of attraction of a saturated system with an algebraic loop. A piecewise quadratic Lyapunov function of an augmented state vector composing of the system state and the saturated input has been proposed for use in estimating the domain of attraction for a saturated system. Considering the relationship between the system states and the saturation function, we propose in this paper a generalized piecewise quadratic Lyapunov function, which results from adding a term that characterizes the regional sector condition of the saturated input to the piecewise quadratic Lypunov function. The matrix associated with the generalized piecewise quadratic Lyapunov function is not required to be positive definite, and thus a set of less conservative stability conditions are established, from which a larger estimate of the domain of attraction can be obtained. Simulation results indicate that the effectiveness and superiority of the proposed method. © 2015

关键词： Lyapunov functions Domain of attraction Input saturation Piece wise quadratic Lyapunov function Positive definite Saturated systems Saturation function Sector condition Stability condition

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Computing finite abstractions with robustness margins via local reachable set over-approximation

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IFAC-PapersOnLine 2015年第27期48卷 1-6页

作者： Li, Yinan Liu, Jun Ozay, Necmiye Department of Automatic Control and System Engineering University of Sheffield SheffieldS1 3JD United Kingdom Department of Applied Mathematics University of Waterloo WaterlooONN2L 3G1 Canada Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States

This paper proposes a method to compute finite abstractions that can be used for synthesizing robust hybrid control strategies for nonlinear systems. Most existing methods for computing finite abstractions utilize some global, analytical function to provide bounds on the reachable sets of nonlinear systems, which can be conservative and lead to spurious transitions in the abstract systems. This problem is even more pronounced in the presence of imperfect measurements and modelling uncertainties, where control synthesis can easily become infeasible due to added spurious transitions. To mitigate this problem, we propose to compute finite abstractions with robustness margins by over-approximating the local reachable sets of nonlinear systems. We do so by linearizing the nonlinear dynamics into linear affine systems and keeping track of the linearization error. It is shown that this approach provides tighter approximations and several numerical examples are used to illustrate of effectiveness of the proposed methods. © 2015, IFAC (International Federation of Automatic control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Robustness (control systems) Abstracting Computation theory Nonlinear systems Numerical methods Temporal logic Uncertainty analysis Abstract systems Analytical functions control synthesis Finite abstraction Hybrid control strategies Linearization errors Reachable set Robustness margins

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Robust decentralized control of large-scale systems via H∞theory and using descriptor system representation

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International Journal of systems Science 2016年第12-13期34卷 705-715页

作者： Labibi, B. Lohmann, B. Sedigh, A. Khaki Maralani, P. Jabedar Control Department Electrical Engineering Faculty K. N. Toosi University of Technology Seyyed Khandan Bridge Shariati Street 16314 Iran Dept. of System Dynamics and Control University of Bremen Otto-Hahn-Allee/NW1 28359 Bremen Germany Electrical and Computer Eng. Dept. Faculty of Engineering University of Tehran North Karegar Street Building No. 2 Tehran Iran

In this paper, a method for design of linear decentralized robust controllers for a class of uncertain large-scale systems in general form is presented. For a given large-scale system, an equivalent descriptor system in input-output decentralized form is defined. Using this representation, closed-loop diagonal dominance sufficient conditions are derived. It is shown that by appropriately minimizing the weighted sensitivity function of each isolated subsystem, these conditions are achieved. Solving the appropriately defined H∞local problem for each isolated uncertain subsystem, the interactions between the subsystems are reduced, and the overall stability and robust performance are achieved in spite of uncertainties. The designs are illustrated by a practical example.

关键词： control system synthesis

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Corrections to "Efficient Adaptive Turbo Equalization for Multiple-Input–Multiple-Output Underwater Acoustic Communications" [W. Duan, J. Tao, and Y. Rosa Zheng, IEEE J. Ocean. Eng ., 2017, DOI: 10.1109/JOE.2017.2707285]

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IEEE Journal of Oceanic engineering 2017年第3期42卷 752-752页

作者： W. Duan J. Tao Y. R. Zheng Qualcomm Technologies Inc. San Diego CA USA Department of Electrical and Computer Engineering Missouri University of Science and Technology Rolla MO USA Key Laboratory of Underwater Acoustic Signal Processing of Ministry of Education Southeast University Nanjing China Key Laboratory of System Control and Information Processing Ministry of Education of China Shanghai China

Equation In [1], (6) of the above named work is corrected.

关键词： MIMO Adaptive equalizers Underwater communication Underwater acoustics Least mean squares methods

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