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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1642-1653页

作者： Zhi Geng Minxiao Han Changjiang Xia Longze Kou School of Electrical and Electronic Engineering North China Electric Power University(NCEPU)Beijing 102206China state key laboratory of Advanced Power transmission Technology Global Energy Interconnection Research InstituteBeijing 102209China

Due to the large number of submodules(SMs),and modular multilevel converters(MMCs)in high-voltage applications,they are usually regulated by the nearest level modulation(NLM).Moreover,the large number of SMs causes a challenge for the fault diagnosis strategy(FDS).This paper proposes a currentless FDS for MMC with *** FDS,the voltage sensor is relocated to measure the output voltage of the *** acquire the capacitor voltage and avoid increasing extra sensors,a capacitor voltage calculation method is *** on the measurement of output voltages,the faults can be detected and the number of different-type switch open-circuit faults can be confirmed from the numerous SMs in an arm,which narrows the scope of fault ***,the faulty SMs and faulty switches in these SMs are further located without arm current according to the sorting of capacitor voltages in the voltage balancing *** FDS is independent of the arm current,which can reduce the communication cost in the hierarchical control system of ***,the proposed FDS not only simplifies the identification of switch open-circuit faults by confirming the scope of faults,but also detects and locates multiple different-type faults in an *** effectiveness of the proposed strategy is verified by the simulation results.

关键词： Fault diagnosis high voltage direct current(HVDC) modular multilevel converter(MMC) nearest level modulation(NLM) switch open-circuit fault

Force Compensation Control for Electro-Hydraulic Servo System with Pump-Valve Compound Drive via QFT-DTOC

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Chinese Journal of mechanical Engineering 2024年第2期37卷 228-246页

作者： Kaixian Ba Yuan Wang Xiaolong He Chunyu Wang Bin Yu Yaliang Liu Xiangdong Kong Hebei Provincial key laboratory of Heavy Machinery Fluid Power transmission and Control Qinhuangdao 066004China School of mechanical Engineering Yanshan UniversityQinhuangdao 066004China National Engineering Research Center for Local Joint of Advanced Manufacturing Technology and Equipment Yanshan UniversityQinhuangdao 066004China

Each joint of a hydraulic-driven legged robot adopts a highly integrated hydraulic drive unit(HDU),which features a high power-weight ***,most HDUs are throttling-valve-controlled cylinder systems,which exhibit high energy *** contrast,pump control systems offer a high ***,their response ability is *** fully utilize the advantages of pump and valve control systems,in this study,a new type of pump-valve compound drive system(PCDS)is designed,which can not only effectively reduce the energy loss,but can also ensure the response speed and response accuracy of the HDUs in robot joints to satisfy the performance requirements of ***,considering the force control requirements of energy conservation,high precision,and fast response of the robot joint HDU,a nonlinear mathematical model of the PCDS force control system is first *** addition,pressure-flow nonlinearity,friction nonlinearity,load complexity and variability,and other factors affecting the system are considered,and a novel force control method based on quantitative feedback theory(QFT)and a disturbance torque observer(DTO)is designed,which is denoted as QFT-DTOC *** method improves the control accuracy and robustness of the force control system,reduces the effect of the disturbance torque on the control performance of the servo motor,and improves the overall force control performance of the ***,experimental verification is performed using the PCDS performance test *** experimental results and quantitative data show that the QFT-DTOC proposed herein can significantly improve the force control performance of the *** relevant force control method can be used as a bottom-control method for the hydraulic servo system to provide a foundation for implementing the top-level trajectory planning of the robot.

关键词： Legged robot Pump-valve compound drive system(PCDS) Force compensation control Quantitative feedback theory(QFT) Disturbance torque observer(DTO)

Dynamic Couplingand Cooperative Control for Multi-paralleled Doubly Fed Induction Generator Wind Farms during Symmetrical Low Voltage Ride-through in a Weak Grid

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Protection and Control of Modern Power Systems 2024年第3期9卷 112-125页

作者： Lei Guan Jun Yao the College of Electrical Engineering at Chongqing University ChongqingChina the state key laboratory of Power transmission Equipment Technology School of Electrical EngineeringChongqing UniversityChongqing 400044China

In multi-fed grid-connected systems,there are complex dynamic interactions between different pieces of *** in situations of weak-grid faults,the dynamic coupling between equipment becomes more *** may cause the system to experience small-signal instability during the fault *** this paper,multi-paralleled doubly fed induction generator(DFIG)-based wind farms(WFs)are taken as an example to study the dynamic coupling within a multi-fed system during fault steady-state of symmetrical low voltage ride-through(LVRT)in a weak *** analysis reveals that the dynamic coupling between WFs will introduce a damping shift to each *** inevitably affects the system’s dynamic stability and brings the risk of small-signal instability during fault steady-state in LVRT *** the distance to fault location and fault severity will exacerbate the dynamic coupling between *** of the dynamic coupling,adjusting the control state of one WF will affect the stability of the remaining WFs in the ***,a cooperative control strategy for multi-paralleled DFIG WFs is proposed to improve dynamic stability during *** analysis and the effectiveness of the proposed control strategy are verified by modal analysis and simu-lation.

关键词： Doubly fed induction generator(DFIG) wind farms(WFs) dynamic stability low voltage ride through(LVRT) weak grid dynamic coupling

Femtosecond laser fabrication of 3D vertically aligned micro-pore network on thick-film Li_(4)Ti_(5)O_(12)electrode for high-performance lithium storage

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Journal of Energy Chemistry 2024年第8期95卷 250-262,I0006页

作者： Quansheng Li Xiaofei Sun Xuesong Mei Lingzhi Wang Minxing Yang Jianlei Cui Wenjun Wang state key laboratory for Manufacturing System Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina Shaanxi key laboratory of Intelligent Robots Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina School of mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina

The development of energy storage devices with high energy density relies heavily on thick film electrodes,but it is challenging due to the limited ion transport kinetics inherent in thick ***,we report on the preparation of a directional vertical array of micro-porous transport networks on LTO electrodes using a femtosecond laser processing strategy,enabling directional ion rapid transport and achieving good electrochemical performance in thick film *** three-dimensional(3D)vertically aligned micro-pore networks are innovatively designed,and the structure,kinetics characteristics,and electrochemical performance of the prepared ion transport channels are analyzed and discussed by multiple characterization and testing ***,the rational mechanisms of electrode performance improvement are studied experimentally and simulated from two aspects of structural mechanics and transmission *** ion diffusion coefficient,rate performance at 60 C,and electrode interface area of the laser-optimized 60-15%micro-porous transport network electrodes increase by 25.2 times,2.2 times,and 2.15 times,respectively than those of untreated ***,the preparation of 3D micro-porous transport networks by femtosecond laser on ultra-thick electrodes is a feasible way to develop high-energy *** addition,the unique micro-porous transport network structure can be widely extended to design and explore other high-performance energy materials.

关键词： Femtosecond laser Micro-porous transport networks Laser processing Thick film electrodes Ion transport kinetics

Generation of orbital angular momentum hologram using a modified U-net

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Chinese Physics B 2024年第3期33卷 401-407页

作者：郑志刚韩菲菲王乐赵生妹 Institute of Signal Processing and transmission Nanjing University of Posts and TelecommunicationsNanjing 210003China key laboratory of Broadband Wireless Communication and Sensor Network Technology (Ministry of Education) Nanjing University of Posts and TelecommunicationsNanjing 210003China National laboratory of Solid state Microstructures Nanjing UniversityNanjing 210093China

Orbital angular momentum(OAM)holography has become a promising technique in information encryption,data storage and opto-electronic computing,owing to the infinite topological charge of one single OAM mode and the orthogonality of different OAM *** this paper,we propose a novel OAM hologram generation method based on a densely connected U-net(DCU),where the densely connected convolution blocks(DCB)replace the convolution blocks of the ***,the reconstruction process of the OAM hologram is integrated into DCU as its output layer,so as to eliminate the requirement to prepare training data for the OAM hologram,which is required by conventional neural networks through an iterative *** experimental and simulation results show that the OAM hologram can rapidly be generated with the well-trained DCU,and the reconstructed image's quality from the generated OAM hologram is significantly improved in comparison with those from the Gerchberg-Saxton generation method,the Gerchberg-Saxton based generation method and the U-net *** addition,a 10-bit OAM multiplexing hologram scheme is numerically demonstrated to have a high capacity with OAM hologram.

关键词： orbital angular momentum(OAM) holography OAM holography deep learning

Exploring reservoir computing:Implementation via double stochastic nanowire networks

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Chinese Physics B 2024年第3期33卷 572-582页

作者：唐健峰夏磊李广隶付军段书凯王丽丹 College of Artificial Intelligence Southwest UniversityChongqing 400715China Brain-inspired Computing & Intelligent Control of Chongqing key laboratory Chongqing 400715China National & Local Joint Engineering laboratory of Intelligent transmission and Control Technology Chongqing 400715China Chongqing Brain Science Collaborative Innovation Center Chongqing 400715China key laboratory of Luminescence Analysis and Molecular Sensing Ministry of EducationSouthwest UniversityChongqing 400715China state key laboratory of Intelligent Vehicle Safety Technology Chongqing 400715China

Neuromorphic computing,inspired by the human brain,uses memristor devices for complex *** studies show that self-organizing random nanowires can implement neuromorphic information processing,enabling data *** paper presents a model based on these nanowire networks,with an improved conductance variation *** suggest using these networks for temporal information processing via a reservoir computing scheme and propose an efficient data encoding method using voltage *** nanowire network layer generates dynamic behaviors for pulse voltages,allowing time series prediction *** experiment uses a double stochastic nanowire network architecture for processing multiple input signals,outperforming traditional reservoir computing in terms of fewer nodes,enriched dynamics and improved prediction *** results confirm the high accuracy of this architecture on multiple real-time series datasets,making neuromorphic nanowire networks promising for physical implementation of reservoir computing.

关键词： double-layer stochastic(DS)nanowire network architecture neuromorphic computation nanowire network reservoir computing time series prediction

mechanical Janus lattice with plug-switch orientation

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Theoretical & Applied Mechanics Letters 2024年第1期14卷 23-26页

作者： Yupei Zhang Jiawei Zhong Zhengcai Zhao Ruiyu Bai Yanqi Yin Yang Yu Bo Li state key laboratory for Manufacturing System EngineeringShaanxi key laboratory of Intelligent Robots School of mechanical Engineering Xi’an Jiaotong UniversityXi’an 710049China Qian Xuesen Honors College Xi’an Jiaotong UniversityXi’an 710049China

In recent years,materials with asymmetric mechanical response properties(mechanical Janus materials)have been found possess numerous potential applications,*** absorption and vibration *** this study,we propose a novel mechanical Janus lattice whose asymmetric mechanical response can be switched in orientation by a *** finite element analysis and experimental verification,this lattice exhibits asymmetric displacement responses to symmetric ***,with such a plug structure inside,individual lattices can switch the orientation of asymmetry and thus achieve reprogrammable design of a mechanical structure with chained *** reprogrammable asymmetry of this material will offer multiple functions in design of mechanical metamaterials.

关键词： Janus Non-reciprocity Programmability mechanical metamaterial

Enhancement of low-temperature toughness of Fe-Mn-C-Al alloy by rare earth Ce-modified inclusions

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Journal of Iron and Steel Research(International) 2024年第1期31卷 157-173页

作者： Guang-kai Yang Chang-ling Zhuang Yi-zhuang Li Chen Hu Shao-bo Li College of Materials and Metallurgy Guizhou UniversityGuiyang550025GuizhouChina Department of mechanical Engineering University of Hong KongHong Kong999077China The state key laboratory of Rolling and Automation Northeastern UniversityShenyang110819LiaoningChina state key laboratory of Public Big Data Guizhou UniversityGuiyang550025GuizhouChina

Fe-Mn-C-Al alloys have been recognized as promising materials for certain low-temperature applications due to their exceptional mechanical properties and ***,their limited low-temperature toughness restricts their large-scale applications in specific *** influence of trace amounts of rare earth cerium(Ce)on the low-temperature toughness of Fe-18Mn-0.6C-1.8Al alloys was *** addition of Ce effectively alters the inclu-sions in the alloy,transforming large-sized irregular inclusions into fine ellipsoidal rare earth *** leads to a significant reduction in both the proportion and average size of the inclusions,resulting in their effective dispersion throughout the matrix and improved cryogenic *** presence of Ce-containing inclusions within the matrix reduces stress concentration,thereby inhibiting microcrack formation and improving impact absorption ***-cally,the addition of rare earth Ce alters the fracture behavior of the material at room temperature and low temperature,changing from brittle cleavage fracture to a more ductile failure *** impact toughness of the Fe-Mn-C-Al alloy is significantly improved by the addition of 0.0048 wt.%Ce,particularly at-196℃where the impact toughness reaches 103.6 J/cm^(2),representing an impressive improvement of 87.3%.

关键词： Fe-Mn-C-Al alloy Rare earth Low-temperature toughness Inclusion Fracture

Influence of Film Thickness on Nanofabrication of Graphene Oxide

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Nanomanufacturing and Metrology 2024年第2期7卷 13-25页

作者： Chuan Tang Lei Chen Linmao Qian Tribology Research Institute The State Key Laboratory of Rail Vehicle SystemSchool of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Nanofabrication of two-dimensional materials through mechanical machining is normally influenced by not only process parameters such as load and velocity but also intrinsic properties such as strength and ***,we examined the effects of graphene oxide(GO)film thickness on nanofabrication on the plane surfaces and at the step edges using scanning probe microscope *** material removal of GO initiates at the load above a critical value,which strongly depends on film thickness and *** the increase in film thickness,the critical load decreases monotonically on the plane surfaces but increases gradually at the step ***,the critical load for the GO monolayer at the step edges is at least 25 times lower than that on the plane surfaces,and the gap decreases to around 3 times when GO thickness increases to four ***,mechanical nanofabrication initiating from the GO step edge allows producing various nanopatterns under extremely low loads around 1 ***,the GO nanostructures are deoxidized by annealing at 800°C in high-purity argon to restore their highly functionalized conjugated structures,which are supported by X-ray diffraction and Raman *** work provides a novel approach to fabricating graphene-like nanostructures by deoxidizing GO after nanofabrication,which holds significant potential for applications in graphene-based devices.

关键词： Graphene oxide Nanofabrication Film thickness step edge Nanopattern Deoxidized treatment

Combined effect of WS_(2) and Ti_(3)C_(2)T_(x) MXene favors oil-based ultra-low friction on rough steel-steel interface at elevated temperatures

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Science China(Technological Sciences) 2024年第7期67卷 1991-2002页

作者： LIU YangQin CHEN Lei WANG Yang QIAN LinMao Tribology Research Institute State Key Laboratory of Rail Transit Vehicle SystemSchool of Mechanical EngineeringSouthwest Jiaotong UniversityChengdu 610031China key laboratory of Advanced Technologies of Materials(Ministry of Education) Research Institute of Frontier ScienceSouthwest Jiaotong UniversityChengdu 610031China

The lubrication performance of liquids is severely restricted and is degraded in high-temperature environments. Stable and reliable lubrication in high temperature environments has been a long-standing goal in various industrial fields. In this study,WS_(2)and Ti_(3)C_(2)T_(x)MXene nanoflakes were used as oil-based lubricant additives to generate ultra-low friction and even superlubricity(friction coefficient of ~0.007) at elevated temperatures(400℃), which has hitherto not been achieved by both individual pristine materials, WS_(2)and Ti_(3)C_(2)T_(x)MXene. Viscosity and thermogravimetric characterization revealed improvements in the high-temperature rheological properties and thermal stability of the lubricating base oil, indicating improved loadbearing and continuous lubrication capabilities at elevated temperatures. X-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy demonstrated that the formation of an iron/titanium/tungsten-rich oxide lubricious thin film at the sliding interface reduced the interfacial shear stress, which was responsible for the observed friction and wear reductions at high contact pressures(> 1.1 GPa). Although the titanium/tungsten oxide film was gradually removed after prolonged sliding, a sufficiently thick iron oxide film maintained a low friction coefficient for at least 2 h. The improved surface quality facilitates the achievement of ultra-low friction and reduced wear. The proposed lubrication methodology has a broad utilization potential as a wear-reduction strategy across various industrial fields at elevated temperatures.

关键词： ultra-low friction high-temperature wear reduction lubricating additive tungsten disulfide MXene