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A voltage support control strategy based on three-port Flexible multi-state switch in distribution networks

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Plasma Science and Technology 2020年第8期22卷 192-202页

作者：彭勃张国荣 School of Electrical Engineering and Automation Hefei University of TechnologyHefei 230009People's Republic of China

Voltage sags in power system may lead to serious problems such as the off-grid of distributed generation and electrical equipment failures.As a novel type of power electronic equipment,a Flexible multi-state switch(FMSS)is capable to support the voltage during the grid faults.In this paper,a voltage control strategy to support the voltage in a distribution network is proposed by introducing three-port FMSS.The positive-negative-sequence compensation(PNSC)scheme is adopted to control the active and reactive current.This control scheme eliminates active power oscillations at the port of voltage sags and reduces coupling oscillations of other ports.Based on the characteristics of the voltage support under PNSC scheme,two voltage support strategies are proposed.A proportional-integral controller is introduced to provide the reactive power references,which eliminates the errors when estimating the grid voltage and impedance.A current limiting scheme is adopted to keep the port current in a safe range by adjusting the active and reactive power references.The voltage support strategies in two different voltage sags are simulated,and results show the feasibility and effectiveness of the proposed control strategies.

关键词： Flexible multi-state switch voltage support low-voltage ride-through reactive power control

Single-step flash-heat synthesis of red phosphorus/ graphene flame-retardant composite as Flexible anodes for sodium-ion batteries

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Nano Research 2018年第7期11卷 3780-3790页

作者： Yihang Liu Anyi Zhang Chenfei Shen Qingzhou Liu Jiansong Cai Xuan Cao Chongwu Zhou Ming Hsieh Department of Electrical Engineering University of Southern California Los Angeles California 90089 USA Mork Family Department of Chemical Engineering and Materials Science University of Southern California Los Angeles California 90089 USA

Red phosphorus （RP） has attracted considerable attention as the anode for high-performance Na-ion batteries, owing to its low cost and high theoretical specific capacity of -2,600 mAh/g. In this study, a facile single-step flash-heat treatment was developed to achieve the reduction of graphene oxide （GO） and the simultaneous deposition of RP onto the reduced graphene oxide （rGO） sheets. The resulting RP/rGO composite was shown to be a promising candidate for overcoming the issues associated with the poor electronic conductivity and large volume variation of RP during cycling. The RP/rGO Flexible film anode delivered an average capacity of 1,625 mAh/g during 200 cycles at a charge/ discharge current density of 1 A/g. Average charge capacities of 1,786, 1,597, 1,324, and 679 mAh/g at 1, 2, 4, and 6 A/g current densities were obtained in the rate capability tests. Moreover, owing to the RP component, the RP/rGO film presented superior flame retardancy compared to an rGO film. This work thus introduces a highly accessible synthesis method to prepare Flexible and safe RP anodes with superior electrochemical performance toward Na-ion storage.

关键词： sodium-ion batteries red phosphorus facile synthesis Flexible flame-retardant reduced graphene oxide

Identification of the state-space model and payload mass parameter of a Flexible space manipulator using a recursive subspace tracking method

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Chinese Journal of Aeronautics 2019年第2期32卷 513-530页

作者： Zhiyu NI Jinguo LIU Zhigang WU Xinhui SHEN State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences State Key Laboratory of Structural Analysis for Industrial Equipment School of Aeronautics and AstronauticsDalian University of Technology

The on-orbit parameter identification of a space structure can be used for the modification of a system dynamics model and controller coefficients. This study focuses on the estimation of a system state-space model for a two-link space manipulator in the procedure of capturing an unknown object, and a recursive tracking approach based on the recursive predictor-based subspace identification(RPBSID) algorithm is proposed to identify the manipulator payload mass parameter. Structural rigid motion and elastic vibration are separated, and the dynamics model of the space manipulator is linearized at an arbitrary working point(i.e., a certain manipulator configuration).The state-space model is determined by using the RPBSID algorithm and matrix transformation. In addition, utilizing the identified system state-space model, the manipulator payload mass parameter is estimated by extracting the corresponding block matrix. In numerical simulations, the presented parameter identification method is implemented and compared with the classical algebraic algorithm and the recursive least squares method for different payload masses and manipulator configurations. Numerical results illustrate that the system state-space model and payload mass parameter of the two-link Flexible space manipulator are effectively identified by the recursive subspace tracking method.

关键词： Flexible space manipulator Linearization Parameter identification State-space model Subspace methods

Submerged Flexible vegetation impact on open channel flow velocity distribution: An analytical modelling study on drag and friction

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Water Science and Engineering 2019年第2期12卷 121-128页

作者： Jaan H. Pu Awesar Hussain Ya-kun Guo Nikolaos Vardakastanis Prashanth R. Hanmaiahgari Dennis Lam Faculty of Engineering and Informatics University of BradfordBradford BD7 1DPUK Department of Civil Engineering Indian Institute of TechnologyKharagpur 721302India

In this paper,an analytical model that represents the streamwise velocity distribution for open channel flow with submerged Flexible vegetation is studied.In the present vegetated flow modelling,the whole flow field has been separated into two layers vertically: a vegetated layer and a non-vegetated free-water layer.Within the vegetated layer,an analysis of the mechanisms affecting water flow through Flexible vegetation has been conducted.In the non-vegetated layer,a modified log-law equation that represents the velocity profile varying with vegetation height has been investigated.Based on the studied analytical model,a sensitivity analysis has been conducted to assess the influences of the drag (CD) and friction (Cf ) coefficients on the flow velocity.The investigated ranges of CD and Cf have also been compared to published values.The findings suggest that the CD and Cf values are non-constant at different depths and vegetation densities,unlike the constant values commonly suggested in literature.This phenomenon is particularly clear for flows with Flexible vegetation,which is characterised by large deflection.

关键词： Analytical model Flexible vegetation Flow velocity Friction Drag Submerged vegetation

Multi-faults diagnosis of rolling bearings via adaptive customization of Flexible analytical wavelet bases

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Chinese Journal of Aeronautics 2020年第2期33卷 407-417页

作者： Chunlin ZHANG Yuling LIU Fangyi WAN Binqiang CHEN Jie LIU Bingbing HU School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China School of Management Northwestern Polytechnical UniversityXi’an 710072China School of Aerospace Engineering Xiamen UniversityXiamen 361005China Department of Mechanical and Aerospace Engineering Carleton UniversityOttawaON K1S5B6Canada Faculty of Printing Packing and Digital Media EngineeringXi’an University of TechnologyXi’an 710048China

Multi-faults detection is a challenge for rolling bearings due to the mode mixture and coupling of multiple fault features,as well as its easy burying in the complex,non-stationary structural vibrations and strong background noises.In this paper,a method based on the Flexible analytical wavelet transform(FAWT)possessing fractional scaling and translation factors is proposed to identify multiple faults occurred in different components of rolling bearings.During the route of the proposed method,the proper FAWT bases are constructed via genetic optimization algorithm(GA)based on maximizing the spectral correlated kurtosis(SCK)which is firstly presented and proved to be efficient and effective in indicating interested fault mode.Via using the customized FAWT bases for each interested fault mode,the original vibration measurements are decomposed into fine frequency subbands,and the sensitive subband which enhances the signal-to-noise ratio(SNR)is selected to exhibit the fault signature on its envelope spectrum.The proposed method is tested via simulated signals,and applied to analyze the experimental vibration measurements from the running roller bearings subjected to outrace,inner-race and roller defects.The analysis results validate the effectiveness of the proposed method in identifying multi-faults occurred in different components of rolling bearings.

关键词： Bearing defect identification Fault diagnosis Flexible analytical wavelet transform Multiple faults Spectral correlated kurtosis

GO-modified Flexible polymer nanocomposites fabricated via 3D stereolithography

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Frontiers of Chemical Science and Engineering 2019年第4期13卷 736-743页

作者： Chi Him Alpha Tsang Adilet Zhakeyev Dennis Y.C.Leung Jin Xuan School of Environmental Sciences and Engineering Sun Yat-Sen UniversityGuangzhou 510006China Department of Mechanical Engineering The University of Hong KongHong KongChina Department of Chemical Engineering Loughborough UniversityLoughboroughLE113TUUK

Graphene oxide(GO)induced enhancement of elastomer properties showed a great deal of potential in recent years,but it is still limited by the barrier of the complicated synthesis processes.Stereolithography(SLA),used in fabrication of thermosets and very recently in“Flexible”polymers with elastomeric properties,presents itself as simple and user-friendly method for integration of GO into elastomers.In this work,it was first time demonstrated that GO loadings can be incorporated into commercial Flexible photopolymer resins to successfully fabricate GO/elastomer nanocomposites via readily accessible,consumer-oriented SLA printer.The material properties of the resulting polymer was characterized and tested.The mechanical strength,stiffness,and the elongation of the resulting polymer decreased with the addition of GO.The thermal properties were also adversely affected upon the increase in the GO content based on differential scanning calorimetry and thermogravimetric analysis results.It was proposed that the GO agglomerates within the 3D printed composites,can result in significant change in both mechanical and thermal properties of the resulting nanocomposites.This study demonstrated the possibility for the development of the GO/elastomer nanocomposites after the optimization of the GO/“Hexible”photoreactive resin formulation for SLA with suitable annealing process of the composite in future.

关键词： graphene oxide polymer Flexible 3D printing stereolithography

Flexible quasi-solid-state dual-ion asymmetric supercapacitor based on Ni（OH）2 and Nb2O5 nanosheet arrays

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Green Energy & Environment 2019年第4期4卷 382-390页

作者： Xiaolan Deng Yuqi Jiang Zengxi Wei Minglei Mao Ramyakrishna Pothu Hongxia Wang Caiyun Wang Jinping Liu Jianmin Ma School of Physics and Electronics Hunan UniversityChangsha410082China School of Chemistry Chemical Engineering and Life Science State Key Laboratory of Advanced Technology for Materials Synthesis and ProcessingWuhan University of TechnologyWuhan430070China School of Chemistry Physics and Mechanical EngineeringQueensland University of TechnologyBrisbaneQLD4001Australia ARC Centre of Excellence for Electromaterials Science Intelligent Polymer Research InstituteAIIMInnovation CampusUniversity of WollongongNorth WollongongNSWAustralia Key Laboratory of Materials Processing and Mold(Zhengzhou University) Ministry of EducationZhengzhou UniversityZhengzhou450002China

Increasing the energy density, power density as well as widening the operation voltage are essential to electrochemical capacitors to meet the practical energy demands. Herein, a novel Flexible quasi-solid-state dual-ion asymmetric supercapacitor(ASC) with Ni(OH)2 and Nb2O5 nanosheets directly grown on stainless steel mesh is developed. In the dual-ion ASC, Nb2O5 negative and Ni(OH)2 positive electrodes react with Li+ and OH- respectively in alkaline gel electrolyte to store energy, which is quite different from conventional alkali metal ion SCs and alkaline SCs. The as-assembled Flexible device has an extended working voltage of 1.7 V and delivers a capacity of 5.37 mAh cm-2, a maximum energy density and power density of 0.52 mWh cm-3 and 170 mW cm-3 , respectively. The device maintains around 60% capacity retention after long cycling up to 1000 cycles. Moreover, our device can light up a LED light efficiently upon fast charging. The proposed quasi-solid-state dual-ion ASC has potential applications in future portable electronics and Flexible energy storage devices.

关键词： Nickel hydroxide Niobium pentoxide Nanoarrays Flexible supercapacitor Dual ion capacitor

Optimization of Ethylene Glycol Doped PEDOT:PSS Transparent Electrodes for Flexible Organic Solar Cells by Drop-coating Method

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Chinese Journal of Polymer Science 2019年第8期37卷 760-766页

作者： Hui-Qin Cui Rui-Xiang Peng Wei Song Jian-Feng Zhang Jia-Ming Huang Li-Qiang Zhu Zi-Yi Ge Faculty of Materials Science and Chemical Engineering Ningbo University Ningbo 315211 China Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China

Fabrication of Flexible transparent electrodes(FTEs) is one of the core technologies in the field of Flexible electronics. Among multiple choices of FTEs, poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonic acid)(PEDOT:PSS) has shown its promising application in roll-to-roll manufacturing. A simple yet effective method for substantially boosting the conductivity of these conducting polymer films without causing large-domain aggregations is by adding ethylene glycol(EG) as dopant. Herein, we investigated in detail the effects of the secondary solvent of ethylene glycol(EG) on the optical and electrical characteristics of PEDOT:PSS films. The modified PEDOT:PSS FTEs were deposited using drop-coating techniques as it had greater compatibility for large-area samples than the conventional spin-coating method did. The 6% EG-doped PEDOT:PSS FTE via drop-coating method achieved a high figure of merit(FoM) value of 47.24 and the devices fabricated using the optimal PEDOT:PSS FTE yielded a high power conversion efficiency(PCE) of 8.89%, mostly attributed to the modified PEDOT:PSS films that had excellent optical and electrical characteristics with low surface roughness. These results suggested that EG-doping could effectively boost the conductivity of PEDOT:PSS films and that the modified PEDOT:PSS FTE is suitable for roll-to-roll manufacturing in the future.

关键词： PEDOT:PSS Doping Conductivity Flexible transparent electrodes Organic solar cells

Flexible sensors based on assembled carbon nanotubes

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Aggregate 2021年第6期2卷 82-98页

作者： Sisi He Yang Hong Meng Liao Yingchun Li Longbin Qiu Huisheng Peng Shenzhen Key Laboratory of Flexible Printed Electronics Technology School of ScienceHarbin Institute of Technology(Shenzhen)ShenzhenChina State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular Scienceand Laboratory of Advanced MaterialsFudan UniversityShanghaiChina Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhenChina

Flexible sensors have attracted significant attention as they could be directly attached to/implanted into the body or incorporated into textiles to monitor human activities and give feedbacks for healthcare.A typical fabrication method is the direct use of intrinsically Flexible active materials such as carbon nanotubes(CNTs).CNTs are generally assembled into aligned structures to extend their remarkable chemical,mechanical,and electrical properties to macroscopic scale to afford high sensing performances.In this review,we present the recent advance of CNT assemblies as electrodes or functional materials for Flexible sensors.The realizations of aligned CNTs are firstly investigated.A variety of Flexible sensors based on the aligned CNTs are then carefully explored,with an emphasis on understanding the working mechanism for their high sensing properties.The main attention is later paid to comparing two main categories of Flexible sensors with fiber and film shapes.The remaining challenges are finally highlighted to offer some insights for future study.

关键词： carbon nanotube Flexible sensor