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The importance of coil conductivity and eddy current effects in the analysis of electromagnetic forming process

High Voltage 2022年第2期7卷 390-404页

作者： Quanliang Cao Liangyu Xia Xian Li Limeng Du Zhipeng Lai Xiaotao Han Liang Li Wuhan National High Magnetic Field Center Huazhong University of Science and TechnologyWuhanChina State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and TechnologyWuhanChina

Coil design and performance analysis are critical for the electromagnetic forming(EMF)***,previous studies have paid little attention to the coil con-ductivity,and the influence of eddy current effects in coil conductors on the forming process has not been well *** work aims to address these problems through numerical and experimental *** is found that,due to the eddy current effects,the uneven current distribution appears in the coil conductors that should be considered when analysing the forming process,especially for the cases with large heights of coil ***,an important and interesting discovery is that the eddy current effects can greatly reduce the sensitivity of the coil conductivity with respect to the workpiece deformation,the Joule heating and the temperature rise in the *** instance,compared to a forming system with a copper coil,the forming height of the workpiece in the forming system with an AA5083‐O coil is reduced by less than 5%under the same discharge energy,while the copper conductivity is 3.3 times that of the *** results are helpful to understand the EMF process and achieve the optimal design of coils.

关键词： conductivity process workpiece

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Controlling of coordination state of Ru_(x)N_(y) clusters for efficient oxygen reduction electrocatalysis

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Nano Research 2024年第3期17卷 1035-1041页

作者： Weiyang Fu Yihuan Yu Tongtong Liu Yinliang Cao Zhengping Zhang Feng Wang State Key Laboratory of Chemical Resource Engineering Beijing Key Laboratory of Electrochemical Process and Technology for MaterialsBeijing University of Chemical TechnologyBeijing 100029China Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China Zhejiang Tianneng Hydrogen Energy Technology Co. Ltd.Huzhou 313100China

Ruthenium(Ru)is an attractive potential alternative to platinum as an electrocatalyst for the oxygen reduction reaction(ORR),in virtue of its high catalytic selectivity and relatively low *** this work,a series of well-dispersed nitrogen-coordinated Ru-clusters on carbon black(Ru_(x)N_(y)/C)were prepared by pyrolyzing different Ru-containing sandwich compounds as the Ru *** higher thermal stability of these complexed sandwich precursors(bis(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)monomer,dichloro(p-cymene)Ru(II)dimer,and chloro(1,2,3,4,5-pentamethylcyclopentadienyl)Ru(II)tetramer)affords the control of coordinated state for the resulting Ru-clusters,in comparison of that derived from ruthenium *** the pyrolysis treatment,the Ru coordinated state in Ru_(x)N_(y)/C,with the Ru–N and Ru–Ru bonds,still showed the structural inheritance from the Ru(II)monomer,dimer,and tetramer,but using ruthenium chlorides as the Ru source resulted in the nanoscale Ru *** ORR testing exhibited that the Ru_(x)N_(y)/C sample derived from the Ru(II)tetramer(Ru_(x)N_(y)/C-T)presents the higher catalytic activity than the other obtained samples in either alkaline or acidic *** in the acidic electrolyte,Ru_(x)N_(y)/C-T shows the comparable ORR activity to that of Pt/C catalysts,and it shows the superior tolerance against methanol and *** X-ray absorption spectroscopy and density functional theory calculations demonstrate that these tetra-nuclear Ru-clusters could be the most active site due to their broadened d-orbital bands and lower energy d-band center than those of other subnano species and nanocrystals,and their favorable Yeager-type adsorption of O_(2)-molecules is also contributed to promoting O–O bond cleavage and accelerating the ORR process.

关键词： ruthenium clusters coordination environment sandwich compounds electrocatalysis oxygen reduction reaction

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A multifunctional electrolyte additive for zinc-ion capacitors with low temperature resistant and long lifespan

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Journal of Energy Chemistry 2024年第7期94卷 477-485页

作者： Ming Sun Zekai Zhang Shuqing Fu Yifan Zhang Ruoyu Wang Hongchun Mu Cheng Lian Wenqiang Wang Gengchao Wang Shanghai Engineering Research Center of Hierarchical Nanomaterials Shanghai Key Laboratory of Advanced Polymeric MaterialsSchool of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China State Key Laboratory of Chemical Engineering Shanghai Engineering Research Center of Hierarchical NanomaterialsFrontiers Science Center for Materiobiology and Dynamic Chemistryand School of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China State Key Laboratory of Molecular Engineering of Polymers Department of Macromolecular ScienceFudan UniversityShanghai 200438China

Aqueous zinc-ion capacitors (ZICs) are considered as potential candidates for next generation electrochemical energy storage devices due to their high safety and low ***,the existing aqueous ZICs usually have the problems of zinc dendrite growth and unsatisfactory performance at low ***,an erythritol (Eryt) additive with inhibition of zinc dendrites and anti-freezing capability was introduced into the *** experimental characterization and theoretical calculation confirm that the Eryt adsorbed on the surface of zinc anodes regulates the deposition orientation of Zn^(2+) and inhibits the formation of *** also reconstructs the solvation structure in the electrolyte to reduce water activity,enabling the electrolyte to have a lower freezing point for operation at low *** the assistance of Eryt,the Zn||Zn symmetric cell exhibits a long cycle life of 2000 h,while the ZIC assembled with activated carbon (AC) cathode and zinc anode (Zn||AC) maintains a capacity retention of 98.2% after 30,000 cycles at a current density of 10 A g^(-1)(even after 10,000 cycles at-20°C,the capacity retention rate reached 94.8%.).This work provides a highly scalable,low-cost and effective strategy for the protection of the anodes of low-temperature aqueous ZICs.

关键词： Zinc-ioncapacitors Electrolyte additive Dendrite-free Freeze-resistant electrolyte

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Nanostructured bimetallic Zn/Co in N-doped carbon as an efficient catalyst for the alcohol dehydrogenation to carboxylic acids under solvent-free conditions

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Journal of Materials Science & technology 2023年第30期161卷 111-122页

作者： Zhong-Hui Zheng Somboon Chaemchuen Jun-Fei Gu Jing Hang Wei Sang Ji-Chao Wang Ye Yuan Cheng Chen State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

The catalytic alcohol dehydrogenation to carboxylic acids has been demonstrated as an atom-economic and environmental-friendly synthetic ***,the reported catalysts either require relatively complicated synthesis or exhibit high activity only in the presence of a ***,it is still in high demand to obtain catalysts that feature facile synthesis and perform well even without any ***,a series of nanostructured bimetallic Zn/Co species embedded in N-doped hierarchical porous carbon were fabricated in a facile and green *** significantly,the best-performing material(Zn/Co@NC-800)was identified as the first heterogeneous catalyst to enable this transformation under solvent-free ***,the as-prepared composites were comprehensively investigated to de-termine their structural and morphological properties,which rationalized the superiority of Zn/Co@NC-800 over the other synthesized *** studies signified that Co sites(both Co^(0)and Co^(2+))and N species(mainly pyridinic N)were probably involved in this process,functioning as the Lewis acid site and basic site,***,this study could provide a simple and sustainable method for carboxylic acid synthesis.

关键词： Heterogeneous catalysis Bimetallic ZIFs Pyrolysis Solvent-free Alcohol dehydrogenation Carboxylic acids

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Preparation and Mechanical Properties of Zirconia Ceramics Doped with Different Y_(2)O_(3)Contents

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Journal of Wuhan University of technology(Materials Science) 2023年第6期38卷 1287-1292页

作者： SONG Yanwei ZHAO Xiaoqing WANG Aiyang XIONG Yan DONG Yanling WANG Weimin State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of Materials and Chemical Engineering Hubei University of TechnologyWuhan 430068China

The sintering behavior and mechanical properties of zirconia doped with 2.0mol%-3.0mol%Y_(2)O_(3)were studied by pressure-less *** experimental results show that the densification temperature of zirconia ceramics increases gradually with the decrease of Y_(2)O_(3)doping content by which decreases the sintering driving force due to the lower oxygen vacancy concentration of the ***,the bending strength and fracture toughness of the prepared zirconia ceramics increase with the decrease of Y_(2)O_(3)doping *** can be attributed to the fact that the phase stability of tetragonal zirconia decreases with the decrease of Y_(2)O_(3)doping content,which is easier to induce"phase transformation toughening"and dissipate impact *** relative density,bending strength and fracture toughness of 2.0 mol%Y_(2)O_(3)doped zirconia ceramics(2.0Y-ZrO_(2))sintered at 1525℃are 99.00%,1256.65±20.82 MPa and 9.85±0.13 MPa·m^(1/2),respectively.

关键词： yttria-stabilized tetragonal zirconia polycrystal(Y-TZP)ceramics sintering behaviors mechanical properties

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Pressureless densification and properties of high-entropy boride ceramics with B_(4)C additions

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Journal of Materials Science & technology 2024年第23期190卷 1-9页

作者： Fawei Wang Liang Xu Ji Zou Jingjing Liu Huayue Liang Wei Ji Weimin Wang Zhengyi Fu Hubei Longzhong Laboratory Wuhan University of Technology Xiangyang Demonstration ZoneXiangyang 441000China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

High entropy boride ceramics have great potential as structural materials serving in extreme ***,their applications are limited by the difficulty of *** the present study,dense(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)ceramics with B_(4)C additions were prepared through pressureless sintering at as low as 1900℃.Calculations based on the CALPHAD approach predict that(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)starts to melt at about 3315℃whilst B_(4)C additions reduce the temperature and broaden the tempera-ture region where solid and liquid *** showed that the introduction of B_(4)C could trigger the densification of(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)at a lower temperature and promote their densification *** relative density of samples with 5 wt%of B_(4)C additions sintered at 1900 and 2000℃was 97.7%and 99.7%,*** the sintering temperature was further increased to 2100℃,the liquid phase was reactively formed,leading to the rapid grain coarsening in samples with B_(4)C *** by well-dispersed B_(4)C grains,the sample with 5 wt%B_(4)C sintered at 2000℃exhibited excellent mechanical properties with the Vickers hardness,flexural strength,and fracture toughness of 21.07±2.09 GPa,547±45 MPa,and 5.24±0.14 MPa m^(1/2),which are comparable or even higher than counterparts sintered under pressure.

关键词： High entropy boride ceramic Microstructure Pressureless sintering Densification Mechanical properties

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High-efficiently doping nitrogen in kapok fiber-derived hard carbon used as anode materials for boosting rate performance of sodium-ion batteries

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Journal of Energy Chemistry 2024年第9期96卷 472-482页

作者： Tianyun Zhang Tian Zhang Fujuan Wang Fen Ran School of Mechanical and Electronical Engineering Lanzhou University of TechnologyLanzhou 730050GansuChina State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals School of Materials Science and EngineeringLanzhou University of TechnologyLanzhou 730500GansuChina

The engineering of plant-based precursor for nitrogen doping has become one of the most promising strategies to enhance rate capability of hard carbon materials for sodium-ion batteries;however,the poor rate performance is mainly caused by lack of pyridine nitrogen,which often tends to escape because of high temperature in preparation process of hard *** this paper,a high-rate kapok fiber-derived hard carbon is fabricated by cross-linking carboxyl group in 2,6-pyridinedicarboxylic acid with the exposed hydroxyl group on alkalized kapok with assistance of zinc ***,a high nitrogen doping content of 4.24%is achieved,most of which are pyridine nitrogen;this is crucial for improving the defect sites and electronic conductivity of hard *** optimized carbon with feature of high nitrogen content,abundant functional groups,degree of disorder,and large layer spacing exhibits high capacity of 401.7 mAh g^(−1)at a current density of 0.05 A g^(−1),and more importantly,good rate performance,for example,even at the current density of 2 A g^(−1),a specific capacity of 159.5 mAh g^(−1)can be *** findings make plant-based hard carbon a promising candidate for commercial application of sodium-ion batteries,achieving high-rate performance with the enhanced pre-cross-linking interaction between plant precursors and dopants to optimize aromatization process by auxiliary pyrolysis.

关键词： Kapok fiber Hard carbon Electrode materials Rate performance Sodium-ion batteries

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Analysis on Circulating Current and Split Capacitor Voltage Balance for Modular Multilevel Converter Based Three-phase Four-wire Split Capacitor DSTATCOM

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Journal of Modern Power Systems and Clean Energy 2021年第3期9卷 657-667页

作者： Lei Lin Jialu He Chen Xu State Key Laboratory of Advanced Electromagnetic Engineering and Technology and School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China

We propose a modular multilevel converter(MMC)based three-phase four-wire(3P4W)split capacitor distribution static synchronous compensator(DSTATCOM),aiming at compensating unbalanced and reactive load *** to the zero-sequence current compensation,the circulating current char-acteristics of 3P4W MMC-DSTATCOM are different from conventional ***,the distinct working principle of IMMC would affect the features of split capacitor *** decoupled positive-,negative-and zero-sequence second-order and DC components of the circulating current are deduced *** proportional-integral controllers with dual dq transformation are employed to suppress the positive-and negative-sequence components of second-order circulating current,while quasi proportional-resonance controller is designed to eliminate the zero-sequence ***,the phenomenon of the unbalanced split capacitor voltages is revealed,and fast-tracking balancing method by controlling zero-sequence current flowing through the split capacitors is *** simulation results verify the accuracy of the analysis and the feasibility of the suppression methods.

关键词： Circulating current modular multilevel converter(MMC) distribution static synchronous compensator(DSTATCOM) split capacitor three-phase four-wire(3P4W)

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Accelerated reconstruction of ZIF-67 with significantly enhanced glucose detection sensitivity

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Nano Research 2024年第6期17卷 4737-4743页

作者： Huihui Jin Weihao Zeng Wei Qian Lun Li Pengxia Ji Zhengying Li Daping He School of Information Engineering Wuhan University of TechnologyWuhan 430070China Hubei Engineering Research Center of RF-Microwave Technology and Application Wuhan University of TechnologyWuhan 430070China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Research on metal-organic framework(MOF)-based non-enzymatic glucose sensors usually ignores the impact of the surface reconstruction degree of MOF on the activity of catalyzing glucose *** this work,we choose zeolitic imidazolate framework-67(ZIF-67),which is commonly used in glucose sensing,as a representative to investigate the influence of reconstruction degree on its structure and glucose catalytic *** employing the electrochemical activation strategy,the activity of ZIF-67 in catalyzing glucose gradually increased with the prolongation of the activation time,reaching the optimum after 2 h *** detection sensitivity of the activated ZIF-67 was 19 times higher than that of the initial ZIF-67,and the limit of detection(LOD)was lowered from 7 to 0.4μ*** findings demonstrate that the oxidation degree of ZIF-67 deepened rapidly with continuously activation and was basically reconstructed to CoOOH after 2 h activation,accompanied by a morphological change from cuboctahedral to ***,theoretical investigation revealed that ZIF-67 is not suitable as a stable glucose sensor electrode since the adsorbed glucose molecules hasten the dissociation of ligands and the breaking of Co-N bond in ***,our work has important implications for the rational design of next-generation MOF-based glucose sensors.

关键词： zeolitic imidazolate framework-67(ZIF-67) glucose oxidation electrochemical activation reconstruction CoOOH

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Energy Procurement and Retail Pricing for Electricity Retailers via Deep Reinforcement Learning with Long Short-term Memory

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CSEE Journal of Power and Energy Systems 2022年第5期8卷 1338-1351页

作者： Hongsheng Xu Jinyu Wen Qinran Hu Jiao Shu Jixiang Lu Zhihong Yang State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical Electronic Engineering Huazhong University of Science and TechnologyWuhan 430074China NARI Group Corporation Nanjing 211106China School of Electrical Engineering Southeast UniversityNanjing 210096China State Key Laboratory of Smart Grid Protection and Control Nanjing 211106China

The joint optimization problem of energy procurement and retail pricing for an electricity retailer is converted into separately determining the optimal procurement strategy and optimal pricing strategy,under the“price-taker”*** aggregate energy consumption of end use customers(EUCs)is predicted to solve for the optimal procurement strategy vis a long short-term memory(LSTM)-based supervised learning *** optimal retail pricing problem is formulated as a Markov decision process(MDP),which can be solved by using deep reinforcement learning(DRL)***,the performance of existing DRL approaches may deteriorate due to their insufficient ability to extract discriminative features from the time-series vectors in the environmental *** propose a novel deep deterministic policy gradient(DDPG)network structure with a shared LSTM-based representation network that fully exploits the Actor’s and Critic’s *** designed shared representation network and the joint loss function can enhance the environment perception capability of the proposed approach and further improve the optimization performance,resulting in a more profitable pricing *** simulations demonstrate the effectiveness of the proposed approach.

关键词： Deep reinforcement learning electricity market energy procurement long short-term memory retail pricing

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