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Enhancing strength and ductility in the nugget zone of friction stir welded 7Mn steel via tailoring austenitic stability

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Journal of Materials Science & Technology 2024年第18期185卷 174-185页

作者： Y.Q.Wang F.Y.Li J.X.Su R.H.Duan Z.A.Luo G.M.Xie State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

The martensite often appears in the nugget zone(NZ)of friction stir welding(FSW)7 wt.%Mn steel due to low austenite stability,deteriorating ductility and *** this work,a 7 wt.%Mn steel was sub-jected to FSW,and preheating was used to tailor the austenitic stability to greatly improve the strength-ductility combination of the *** austenitic deformation behavior and strain hardening mechanism in the NZ were systematically *** microstructure of the as-welded NZ was composed of ultrafine blocky ferrite,austenite,and small amounts of martensite,whereas the as-preheated NZ con-tained ultrafine blocky ferrite and austenite,and the concentration of Mn in austenite was increased from 8.4 wt.%to 10.7 wt.%.This enhanced the austenitic stability,resulting in a significant increase in the volume fraction of austenite in the as-preheated NZ from 37.3%to 66.4%.The product of strength and elongation(PSE)in the as-preheated NZ increased dramatically from 42.6 GPa%to 67.1 GPa%,depending on a persistent high strain hardening rate(SHR).Multiple strain-hardening mechanisms were *** austenite with enhanced stability can provoke sustained transformation-induced plasticity(TRIP)and twinning-induced plasticity(TWIP)effects,and massive dislocation multiplication occurs during tension,resulting in strong strain hardening.

关键词： Friction stir welding Medium Mn steel Preheating Transformation-induced plasticity Twinning-induced plasticity

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Event-Triggered Adaptive Prescribed-Time Tracking for Nonlinear Systems With Non-vanishing Uncertainties

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IEEE Transactions on Automatic Control 2025年第6期70卷 4140-4147页

作者： Zhang, Cui-Hua Li, Yu-Jia Hua, Chang-Chun Sun, Zong-Yao Zhang, Ying Yanshan University School of Electrical Engineering Qinhuangdao066004 China Qufu Normal University Institute of Automation Shandong Qufu273165 China

This paper solves the problem of prescribed-time (PT) prescribed-performance tracking for a class of nonlinear systems with non-vanishing uncertainties based on a finite-time command filter (FTCF). To deal with non-vanishing uncertainties, a novel PT stabilization criterion that incorporates an adaptive method is proposed and a compensation mechanism is established to reduce the errors caused by FTCF, where the parameter adaptive estimation error achieves asymptotically-zero convergence. Based on this, an event-triggered PT control strategy is designed to ensure that the closed-loop system achieves PT prescribed-performance tracking, in which a new relative-threshold event-triggered mechanism (ETM) is constructed to better balance event-triggered errors and saving communication resources. Unlike the existing methods, the proposed method not only guarantees a more accurate control performance that the tracking error reaches zero at the prescribed time moment, but also reduces the computational complexity by pioneering the introduction of FTCF. The effectiveness of the proposed method is verified by experiments. © 1963-2012 IEEE.

关键词： Adaptive filters

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Ultimately Bounded Output Feedback Control for Networked Nonlinear Systems With Unreliable Communication Channel: A Buffer-Aided Strategy

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IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1566-1578页

作者： Yuhan Zhang Zidong Wang Lei Zou Yun Chen Guoping Lu the College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266590China IEEE the Department of Computer Science Brunel UniversityUB83PHUnited Kingdom the College of Information Science and Technology Donghua UniversityShanghai 201620 the Engineering Research Center of Digitalized Textile and Fashion Technology Ministry of EducationShanghai 201620China the School of Automation Hangzhou Dianzi UniversityHangzhou 310018China the School of Electrical Engineering Nantong UniversityNantong 226019China

This paper concerns ultimately bounded output-feedback control problems for networked systems with unknown nonlinear dynamics. Sensor-to-observer signal transmission is facilitated over networks that has communication *** transmissions are carried out over an unreliable communication channel. In order to enhance the utilization rate of measurement data, a buffer-aided strategy is novelly employed to store historical measurements when communication networks are inaccessible. Using the neural network technique, a novel observer-based controller is introduced to address effects of signal transmission behaviors and unknown nonlinear *** the application of stochastic analysis and Lyapunov stability, a joint framework is constructed for analyzing resultant system performance under the introduced controller. Subsequently, existence conditions for the desired output-feedback controller are delineated. The required parameters for the observerbased controller are then determined by resolving some specific matrix inequalities. Finally, a simulation example is showcased to confirm method efficacy.

关键词： Buffer-aided strategy neural networks nonlinear control output-feedback control unreliable communication channel

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State Transition Modeling Method for Optimal Dispatching for Integrated Energy System Based on Cyber-Physical System

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Journal of Modern Power Systems and Clean Energy 2024年第5期12卷 1617-1630页

作者： Yi Yang Peng Zhang Can Wang Zhuoli Zhao Loi Lei Lai the Hubei Provincial Key Laboratory for Operation and Control of Cascaded Hydropower Station College of Electrical Engineering and New EnergyChina Three Gorges UniversityYichangChina the Department of Electrical Engineering School of AutomationGuangdong University of TechnologyGuangzhouChina

The traditional energy hub based model has difficulties in clearly describing the state transition and transition conditions of the energy unit in the integrated energy system(IES).Therefore,this study proposes a state transition modeling method for an IES based on a cyber-physical system(CPS)to optimize the state transition of energy unit in the *** method uses the physical,integration,and optimization layers as a three-layer modeling *** physical layer is used to describe the physical models of energy units in the *** the integration layer,the information flow is integrated into the physical model of energy unit in the IES to establish the state transition model,and the transition conditions between different states of the energy unit are *** optimization layer aims to minimize the operating cost of the IES and enables the operating state of energy units to be transferred to the target *** simulations show that,compared with the traditional modeling method,the state transition modeling method based on CPS achieves the observability of the operating state of the energy unit and its state transition in the dispatching cycle,which obtains an optimal state of the energy unit and further reduces the system operating costs.

关键词： Integrated energy system(IES) cyber-physical system(CPS) state transition modeling optimal dispatching

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Application Research of FPGA-DSP Architecture in Ship Radar Signal Processing 14

Application Research of FPGA-DSP Architecture in Ship Radar ...

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14th International Conference on Electronics, Communications and Networks, CECNet 2024

作者： Hang, Zongpeng Liu, Yongchun Peng, Xin Zeng, Haixin Lu, Weian School of Physics and Electronic Engineering Sichuan University of Science & Engineering Yibin644002 China School of Automation and Information Engineering Sichuan University of Science & Engineering Yibin644002 China

ISBN: (纸本)9781643685632

In view of the continuous improvement of maritime safety requirements, the demand for maritime radar signal processing system is increasing day by day. A ship radar Signal processing system based on Field-Programmable Gate Array (FPGA) and Digital Signal Processor (DSP) is designed in this paper. The system design covers the construction of hardware architecture and the realization of signal processing algorithm. Through the advantages of FPGA in parallel processing and logic realization, and the powerful ability of DSP in high-speed mathematical operation and signal processing algorithm, the high-speed data interaction of ship and ship system is realized. The stability of the system is verified by simulation and measured data. The results show that the system can effectively process the radar echo signal, realize the rapid and accurate detection of Marine targets, and perform well in clutter suppression. The design of this paper not only meets the needs of modern ship radar signal processing, but also provides a new idea and technical reference for the research of related fields. © 2024 The Authors.

关键词： Radar clutter

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Distributed Multicircular Circumnavigation Control for UAVs with Desired Angular Spacing

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Defence Technology（防务技术） 2024年第1期31卷 429-446页

作者： Shixiong Li Xingling Shao Wendong Zhang Qingzhen Zhang National Key Laboratory for Electronic Measurement Technology School of Instrument and ElectronicsNorth University of ChinaTaiyuan 030051China School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100086China

This paper addresses a multicircular circumnavigation control for UAVs with desired angular spacing around a nonstationary *** defining a coordinated error relative to neighboring angular spacing,under the premise that target information is perfectly accessible by all nodes,a centralized circular enclosing control strategy is derived for multiple UAVs connected by an undirected graph to allow for formation behaviors concerning the moving ***,to avoid the requirement of target’s states being accessible for each UAV,fixed-time distributed observers are introduced to acquire the state estimates in a fixed-time sense,and the upper boundary of settling time can be determined offline irrespective of initial properties,greatly releasing the burdensome communication ***,with the aid of fixed-time distributed observers,a distributed circular circumnavigation controller is derived to force all UAVs to collaboratively evolve along the preset circles while keeping a desired angular *** is inferred from Lyapunov stability that all errors are demonstrated to be *** are offered to verify the utility of proposed protocol.

关键词： Angular spacing Distributed observer Multicircular circumnavigation Moving target UAVs

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Multispectral point cloud superpoint segmentation

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Science China(Technological Sciences) 2024年第4期67卷 1270-1281页

作者： WANG QingWang WANG MingYe ZHANG ZiFeng SONG Jian ZENG Kai SHEN Tao GU YanFeng Faculty of Information Engineering and Automation Kunming University of Science and TechnologyKunming 650500China Yunnan Key Laboratory of Computer Technologies Application Kunming 650500China School of Electronics and Information Engineering Harbin Institute of TechnologyHarbin 150001China

The multitude of airborne point clouds limits the point cloud processing *** are grouped based on similar points,which can effectively alleviate the demand for computing resources and improve processing ***,existing superpoint segmentation methods focus only on local geometric structures,resulting in inconsistent spectral features of points within a *** feature inconsistencies degrade the performance of subsequent ***,this study proposes a novel Superpoint Segmentation method that jointly utilizes spatial Geometric and Spectral Information for multispectral point cloud superpoint segmentation(GSI-SS).Specifically,a similarity metric that combines spatial geometry and spectral information is proposed to facilitate the consistency of geometric structures and object attributes within segmented *** the formation of the primary superpoints,an intersuperpoint pointexchange mechanism that maximizes feature consistency within the final superpoints is *** are conducted on two real multispectral point cloud datasets,and the proposed method achieved higher recall,precision,F score,and lower global consistency and feature classification *** experimental results demonstrate the superiority of the proposed GSI-SS over several state-of-the-art methods.

关键词： multispectral point cloud superpoint segmentation over-segmentation spatial-spectral joint metric

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A Non-Iterative Network Utilization Pricing Mechanism for P2P Energy Trading

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1301-1306页

作者： Yun Liu Yunqiang Gao Yuanzheng Li Jizhong Zhu Hoay Beng Gooi School of Electric Power Engineering South China University of TechnologyGuangzhou 510641China School of Artificial Intelligence and Automation Ministry of Education Key Laboratory of Image Processing and Intelligence ControlHuazhong University of Science and TechnologyWuhan 430074China School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore IEEE

To sustain operation and maintenance of an active distribution network(ADN),a network fee should be charged by the distribution network service provider(DNSP)for facilitating the P2P energy trading *** this end,this paper models the interaction among the DNSP and multiple prosumers as a Stackelberg game,and then develops a non-iterative and decentralized transactive mechanism to simultaneously achieve optimal network utilization pricing and peer-to-peer(P2P)*** results in an ADN with four prosumers connected to a common substation bus validate the effectiveness and efficiency of the proposed scheme.

关键词： Distribution network service provider network fee non-iterative peer-to-peer trading prosumer

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Segment differential aggregation representation and supervised compensation learning of ConvNets for human action recognition

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Science China(Technological Sciences) 2024年第1期67卷 197-208页

作者： REN ZiLiang ZHANG QieShi CHENG Qin XU ZhenYu YUAN Shuai LUO DeLin School of Computer Science and Technology Dongguan University of TechnologyDongguan 523808China Shenzhen Institute of Advanced Technology Chinese Academy of SciencesShenzhen 518055China School of Electronic Engineering and Automation Guilin University of Electronic TechnologyGuilin 541004China Department of the mechanical engineering Erlangen-Nuremberg UniversityErlangen 91508Germany School of Aerospace Engineering Xiamen UniversityXiamen 361102China

With more multi-modal data available for visual classification tasks,human action recognition has become an increasingly attractive ***,one of the main challenges is to effectively extract complementary features from different modalities for action *** this work,a novel multimodal supervised learning framework based on convolution neural networks(Conv Nets)is proposed to facilitate extracting the compensation features from different modalities for human action *** on information aggregation mechanism and deep Conv Nets,our recognition framework represents spatial-temporal information from the base modalities by a designed frame difference aggregation spatial-temporal module(FDA-STM),that the networks bridges information from skeleton data through a multimodal supervised compensation block(SCB)to supervise the extraction of compensation *** evaluate the proposed recognition framework on three human action datasets,including NTU RGB+D 60,NTU RGB+D 120,and *** results demonstrate that our model with FDA-STM and SCB achieves the state-of-the-art recognition performance on three benchmark datasets.

关键词： action recognition segment frame difference aggregation supervised compensation learning ConvNets

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Mitigation of Deane and Hamill phenomenon in gallium nitride high-voltage power supply for electric propulsion system application

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High Voltage 2024年第1期9卷 252-265页

作者： Minghai Dong Hui Li Shan Yin Kye Yak See Yingzhe Wu Xiong Xin School of Aeronautics&Astronautics University of Electronic Science and Technology of ChinaChengduChina School of Electrical&Electronic Engineering Nanyang Technological UniversitySingaporeSingapore School of Automation Engineering University of Electronic Science and Technology of ChinaChengduChina Innoscience(Shenzhen)Semiconductor Co.Ltd. ShenzhenChina

The step-up resonant converters are widely adopted to provide high voltage in kV-level for electric propulsion system due to their high efficiency,low mass,modularisation,and high-power *** bipolar Cockcroft-Walton voltage multiplier(BiCWVM)is a major circuit that steps up the voltage in the resonant ***,the diode nonlinearity in BiCWVM can introduce self-sustained quasi-periodic oscillations in the voltage and current waveforms,which is commonly known as the Deane and Hamill(DH)*** oscillation can lead to higher magnetic loss and control failure,and it is more likely to present in the gallium nitride-based converter due to the highfrequency *** authors aim to investigate and mitigate the DH phenomenon systematically so that proper mitigation can be *** facilitate the investigation,the circuit before the BiCWVM in the converter is derived and modelled as a voltage source v_(m)and a series inductor L_(sy).Also,the reverse recovery process of the diode in the BiCWVM can be represented by a piecewise-linear(PWL)model,with the simplified circuit and PWL model,the relationship between voltage and current under different operating conditions can be determined with *** relationship allows to understand the mechanism of diode reverse recovery in BiCWVM that leads to DH ***,a hybrid-/full-silicon carbide(SiC)design is proposed to mitigate the DH phenomenon,which is verified experimentally for a 300-kHz,5-W,20-V/1.5-kV GaN-based step-up resonant converter.

关键词： power resonant high

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