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Fuzzy Static Output Feedback H_∞ Control for Nonlinear Systems Subject to Parameter Uncertainties

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Journal of Systems Science & Complexity 2018年第2期31卷 343-371页

作者： zhao tao DIAN Songyi School of Electrical Engineering and Information Sichuan University

This study is concerned with the stabilization issue of nonlinear systems subject to parameter uncertainties. An interval type-2 T-S fuzzy model is used to represent the nonlinear systems subject to parameter uncertainties. An interval type-2 fuzzy static output feedback controller is designed to synthesize the interval type-2 T-S fuzzy systems. The membership-function-dependent stability conditions are derived by utilizing the information of upper and lower membership functions. The proposed stability conditions are presented in the form of linear matrix inequalities（LMIs）. LMI-based stability conditions for interval type-2 fuzzy static output feedback H_∞ control synthesis are also *** simulation examples are given to show the superiority of the proposed approach.

关键词： Interval type-2 fuzzy controller parameter uncertainties static output feedback control T-S fuzzy systems.

A New Class for Large Sets of Almost Hamilton Cycle Decompositions

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Acta Mathematicae Applicatae Sinica 2017年第4期33卷 865-870页

作者： Hong-tao zhao School of Mathematics and Physics North China Electric Power University Beijing 102206 China

A k-cycle system of order v with index A, denoted by CS（v, k, λ）, is a collection A of k-cycles （blocks） of Kv such that each edge in Kv appears in exactly λ blocks of A. A large set of CS（v, k, λ）s is a partition of the set of all k-cycles of Kv into CS（v, k, λ）s, and is denoted by LCS（v, k, λ）. A （v - 1）-cycle in K, is called almost Hamilton. The completion of the existence problem for LCS（v, v- 1,λ） depends only on one case： all v ≥ 4 for λ=2. In this paper, it is shown that there exists an LCS（v,v - 1,2） for all v ≡ 2 （mod 4）, v ≥ 6.

关键词： large set cycle system almost Hamilton cycle decomposition symmetric group complete auto-morphism group

Algebraic Method‑Based Point‑to‑Point Trajectory Planning of an Under‑Constrained Cable‑Suspended Parallel Robot with Variable Angle and Height Cable Mast

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Chinese Journal of Mechanical Engineering 2020年第4期33卷 45-62页

作者： tao zhao Bin Zi Sen Qian Jiahao zhao School of Mechanical Engineering Hefei University of TechnologyHefei 230009China Chemical Science and Engineering College North Minzu UniversityYinchuan 750021China

To avoid impacts and vibrations during the processes of acceleration and deceleration while possessing flexible working ways for cable-suspended parallel robots(CSPRs),point-to-point trajectory planning demands an under-constrained cable-suspended parallel robot(UCPR)with variable angle and height cable mast as described in this *** end-effector of the UCPR with three cables can achieve three translational degrees of freedom(DOFs).The inverse kinematic and dynamic modeling of the UCPR considering the angle and height of cable mast are *** motion trajectory of the end-effector comprising six segments is *** connection points of the trajectory segments(except for point P3 in the X direction)are devised to have zero instantaneous velocities,which ensure that the acceleration has continuity and the planned acceleration curve achieves smooth *** trajectory is respectively planned using three algebraic methods,including fifth degree polynomial,cycloid trajectory,and double-S velocity *** results indicate that the trajectory planned by fifth degree polynomial method is much closer to the given trajectory of the *** simulation and experiments are accomplished for the given trajectory based on fifth degree polynomial *** the points where the velocity suddenly changes,the length and tension variation curves of the planned and unplanned three cables are compared and *** OptiTrack motion capture system is adopted to track the end-effector of the UCPR during the *** effectiveness and feasibility of fifth degree polynomial planning are validated.

关键词： Under-constrained cable-suspended parallel robot Variable angle and height cable mast Inverse kinematic and dynamic modeling Algebraic method Point-to-point trajectory planning

Active event-driven reliable defense control for interconnected nonlinear systems under actuator faults and denial-of-service attacks

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Science China(Information Sciences) 2022年第6期65卷 155-171页

作者： Bin GUO Songyi DIAN tao zhao College of Electrical Engineering Sichuan University

This study investigates the reliable control design for a class of interconnected nonlinear systems subjected to actuator faults, disturbances, and denial-of-service(DoS) attacks. DoS attacks are carried out in both sensor and controller channels. An integrated event-observer-based security sliding mode fault-tolerant control approach is presented to defend against DoS attacks and compensate for faults and *** be more specific, the fuzzy logic system(FLS) theory is used to approximate the unknown nonlinear component first. Using the output measurement and sensor channel triggered output information, an FLS aided nonlinear estimator is put forward, in which the faults and disturbances are reconstructed. Then, to achieve the trajectory tracking purpose in the presence of DoS attacks, actuator faults, and disturbances, an adaptive sliding mode manifold is established, based on which an event-driven mechanism is established and a reliable controller is designed. In the controller scheme, the fault compensation and disturbance rejection mechanisms are also included synchronously. The tracking ability is analyzed using the Lyapunov method and the FLS theory, followed by applications to an interconnected power network system and an interconnected inverted pendulum system to demonstrate the applicability of the proposed method.

关键词： interconnected nonlinear system actuator fault DoS attack disturbance fault-tolerant control event-driven control

Applications of chemical imaging techniques in paleontology

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National Science Review 2019年第5期6卷 1040-1053页

作者： Yanhong Pan Liang Hu tao zhao CAS Key Laboratory of Economic Stratigraphy and Palaeogeography Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and PaleoenvironmentChinese Academy of Sciences University of Chinese Academy of Sciences State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and PaleoenvironmentChinese Academy of Sciences

Chemical imaging techniques, based on a combination of microscopy and spectroscopy, are designed to analyse the composition and spatial distribution of heterogeneous chemical complexes within a *** the last few decades, it has become an increasingly popular tool for characterizing trace elements,isotopic information and organic biomarkers(molecular biosignatures) found in ***, we introduce the analytical principle of each technique and the interpretation of the chemical signals, followed by a review of the main applications of these techniques in *** also demonstrate that each technique is associated with pros and cons, and the current limitations and obstacles associated with the use of each specific technique should be taken into account before being applied to fossil ***, we propose that, due to the rapid advances in the available technology and overall trends towards more multi-disciplinary studies in paleontology, chemical imaging techniques can be expected to have broader applications in paleontology in the near future.

关键词： trace elements isotopic information organic biomarkers fossil materials limits and obstacles

Cherenkov terahertz radiation from Dirac semimetals surface plasmon polaritons excited by an electron beam

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Chinese Physics B 2020年第3期29卷 176-180页

作者： tao zhao Zhenhua Wu Terahertz Research Center School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu 610054China

We demonstrate a physical mechanism for terahertz(THz) generation from surface plasmon polaritons(SPPs). In a structure with a bulk Dirac semimetals(BDSs) film deposited on a dielectric substrate, the energy of the asymmetric SPP mode can be significantly enhanced to cross the light line of the substrate due to the SPP-coupling between the interfaces of the film. Therefore, the SPPs can be immediately transformed into Cherenkov radiation without removing the wavevector mismatch. Additionally, the symmetric SPP mode can also be dramatically lifted to cross the substrate light line when a buffer layer with low permittivity relative to the substrate is introduced. In this case, dual-frequency THz radiation from the two SPP modes can be generated simultaneously. The radiation intensity is significantly enhanced by over two orders due to the field enhancement of the SPPs. The radiation frequency can be tuned in the THz frequency regime by adjusting the beam energy and the chemical potential of the BDSs. Our results could find potential applications in developing room temperature, tunable, coherent, and intense THz radiation sources to cover the entire THz band.

关键词： terahertz radiation sources surface plasmon polaritons Cherenkov radiation

Fracture prediction in the tight-oil reservoirs of the Triassic Yanchang Formation in the Ordos Basin,northern China

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Petroleum Science 2017年第1期14卷 1-23页

作者： Wen-tao zhao Gui-Ting Hou The Key Laboratory of Orogenic Belts and Crustal Evolution of Ministry of Education School of Earth and Space SciencesPeking UniversityBeijing 100871China China Huaneng Clean Energy Research Institute Beijing 102209China Petro China Research Institute of Petroleum Exploration and Development Beijing 100083China

It is important to predict the fracture distribution in the tight reservoirs of the Ordos Basin because fracturing is very crucial for the reconstruction of the low-permeability reservoirs. Three-dimensional finite element models are used to predict the fracture orientation and distribution of the Triassic Yanchang Formation in the Longdong area, southern Ordos Basin. The numerical modeling is based on the distribution of sand bodies in the Chang 7a and 72 members, and the different forces that have been exerted along each boundary of the basin in the Late Mesozoic and the Cenozoic. The calculated results demonstrate that the fracture orientations in the Late Mesozoic and the Ceno- zoic are NW-EW and NNE-ENE, respectively. In this paper, the two-factor method is applied to analyze the distribution of fracture density. The distribution maps of predicted fracture density in the Chang 71 and 72 members are obtained, indicating that the tectonic movement in the Late Mesozoic has a greater influence on the fracture development than that in the Cenozoic. The average fracture densities in the Chang 71 and 72 members are similar, but there are differences in their distributions. Compared with other geological elements, the lithology and the layer thickness are the primary factors that control the stress distribution in the study area, which further determine the fracture distribution in the stable Ordos Basin. The predicted fracture density and the two-factor method can be utilized to guide future exploration in the tight-sand reservoirs.

关键词： Ordos Basin - Yanchang Formation Fractureprediction Finite element modeling Two-factor methodTight-sand reservoirs

Ag nanoparticles anchored on MIL-100/nickel foam nanosheets as an electrocatalyst for efficient oxygen evolution reaction performance

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Chinese Journal of Chemical Engineering 2022年第1期35卷 480-487页

作者： tao zhao Dazhong Zhong Genyan Hao Guang Liu Jinping Li Qiang zhao Shanxi Key Laboratory of Gas Energy Efficient and Clean Utilization College of Chemistry and Chemical EngineeringTaiyuan University of TechnologyTaiyuan 030024China

Metal-organic frameworks(MOFs)exhibit excellent application potential in the field of *** this study,we first prepare MIL-100 nanosheets on nickel foam(MIL-100/NF)and then successfully anchor Ag nanoparticles(NPs)on the nanosheets(Ag@MIL-100/NF)for oxygen evolution reaction(OER)*** strategy dramatically improves the conductivity of MIL-100 and the Ag NPs are uniformly dispersed on the *** Ag@MIL-100/NF catalyst has excellent electrocatalytic performance and long-term corrosion resistance,with a low overpotential of 207 mV and a long-term stability of at least 100 h at a current density of 50 mA·cm^(-2).The experimental results demonstrate that this high OER catalytic performance is due to the improved charge transfer after loading Ag NPs,the combination of nanosheets and highly dispersed Ag NPs that expose more active sites and the adjusted chemical valence states of Fe and Ni in *** work provides a surface decoration approach for the preparation of excellent catalysts directly used in the OER.

关键词： Ag@MIL-100/NF Metal-organic frameworks Catalysis Kinetics Overpotential Electrochemistry

On Weakly Normal Subgroups of a Finite Group

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Algebra Colloquium 2014年第3期21卷 527-533页

作者： Yong Xu Xinjian Zhang tao zhao School of Mathematics and Statistics Henan University of Science and Technology Luoyang Henan 471023 China School of Mathematics Huaiyin Normal University Huaian Jiangsu 223300 China School of Science Shandong University of Technology Zibo Shandong 255049 China

A subgroup H of a group G is said to be weakly normal in G if Hg ≤ NG（H） implies that g E NG（H）. In this paper, using the condition that the minimal subgroups or subgroups of prime square order of G are weakly no... 详细信息

关键词： formation weakly normal subgroup F-hypercentral