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Dense carbon nanofiber self-supporting electrode fabricated by orientation/compaction strategy for high volumetric lithium storage capacity

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Progress in Natural Science:Materials International 2025年第1期35卷 229-237页

作者： Haihui Liu Chaoqun Chen Qiang Xu Yan Song Xiangwu Zhang Chang Ma Tianjin Municipal Key Lab of Advanced Fiber and Energy Storage Technology Tiangong University CAS Key Laboratory of Carbon Materials Institute of Coal Chemistry Chinese Academy of Sciences Fiber and Polymer Science Program Department of Textile Engineering Chemistry and Science Wilson College of Textiles North Carolina State University

Low bulk density greatly restricts the large-scale application of electrospun carbon-based fiber membrane as electrode in energy storage devices. To solve the above challenges, herein an orientation-compaction densification strategy is proposed to enhance the bulk density and volumetric capacity of PAN-based carbon nanofiber membranes as self-supporting electrode used in lithium-ion batteries（LIBs）. Specifically, highly-oriented fibers are achieved by high-speed roller collecting during electrospinning, and compaction densification is conducted by hot-pressing treatment. The effects of collecting speed and hot-pressing pressure on the morphology, conductivity,bulk density, tensile strength, and flexibility of the obtained carbon nanofiber membrane are *** to conventional fiber membranes, of which fibers are disorderly stacked, the oriented fiber membrane is much easier to achieve dense stacking by compaction. The obtained dense carbon nanofiber membrane demonstrates a bulk density of 0.566 g cm-3, and shows a significantly-enhanced volumetric capacity(318.3 mA h cm-3), high-rate performance(86.6 mA h cm-3at 5 A g-1), and satisfactory cycling stability when used as selfsupporting electrode of LIBs.

关键词： Bulk density Densification Electrospinning Orientation-compaction Volumetric capacity

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Start-to-end simulation for a compact terahertz free electron laser with a beam chopper system

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Nuclear Science and Techniques 2025年第7期36卷 1-11页

作者： Luo, Rui-Ying Chen, Qu-Shan State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

A thermionic gun is endowed with a long bunch tail, which presents challenges for the compact terahertz free electron laser (FEL) facility at the Huazhong University of Science and technology. Owing to a large energy spread, the tail particles do not contribute to the radiation. In the original design, an x-direction slit is used in the dispersive section of the transport line to remove the tail particles. This paper presents an improved scheme to remove the tail by introducing an RF beam chopper system at the exit of the electron gun, to prevent a significant number of tail particles from entering the linac. The facility remains compact while effectively removing the tail of the bunch. The parameters of the beam chopper system are designed. Bunch parameters and radiation performance are analyzed via a start-to-end simulation. The findings indicate that 43% of the particles can pass through the beam chopper system for subsequent acceleration and transport, which saves the RF power, reduces beam loss in the linac, reduces background noise, and suppresses the sideband instability. Simultaneously, the beam chopper system causes an increase in beam emittance, energy spread, and an offset in the center of the bunch. These effects can be mitigated by a solenoid, linac, and steering coils. The simulation results for the FEL show that the micro-pulse energy is greater than 1.1 μJ in the frequency range of 2.8–9.7 THz, and the maximum micro-pulse energy is 1.28 μJ. © The Author(s), under exclusive licence to China Science Publishing & Media Ltd. (Science Press), Shanghai Institute of Applied Physics, the Chinese Academy of Sciences, Chinese Nuclear Society 2025.

关键词： Particle beam bunching

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Research on 1050 nm high-power narrow linewidth fiber laser based on tapered ytterbium-doped fiber 7

Research on 1050 nm high-power narrow linewidth fiber laser ...

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7th Optics Young Scientist Summit, OYSS 2024

作者： Ye, Yun Wang, Xiaolin Wang, Yanbin Zhou, Xuanfeng Jiang, Chenglong Zhang, Defeng Xi, Xiaoming Xu, Xiaojun State Key Lab. of Complex Electromagnetic Environment Effects on Electronics and Information System Luoyang471003 China College of Advanced Interdisciplinary Studies National University of Defense Technology Changsha410073 China

ISBN: (数字)9781510688377

ISBN: (纸本)9781510688360

Compared to conventional uniform fibers, long tapered Yb-doped fibers (T-YDF) have outstanding potential to alleviate the detrimental nonlinear effects due to their unique mode field characteristics along the length direction. In this work, an T-YDF-based short-wavelength narrow linewidth monolithic fiber amplifier was constructed through one-stage MOPA configuration. The fiber amplifier emits at the central wavelength of ~1050 nm, and the output lasing performance is carefully studied for different pumping scheme. The experimental results indicated that compared with the co-pumping scheme, the counter-pump one holds a better properties involving spectral broadening suppression, SRS suppression and TMI threshold enhancement in the 1050 nm narrow-linewidth fiber lasers. As a result, an output power of 3.56 kW was achieved with a slope efficiency of ~83.6% by adopting bidirectional pumping scheme. At the maximum lasing power, the 3dB spectral linewidth was measured ~0.58 nm, and the SRS suppression ratio was greater than ~27.3dB. This work could offer a promising approach for extending the operating wavelength of high-power narrow linewidth fiber lasers. © 2025 SPIE.

关键词： Fiber lasers

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In-situ growth of cross-link NiAl-LDH nanosheets on the inner/outer surfaces of carbon microtubes for anti-corrosive electromagnetic wave absorption

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Journal of Materials Science and technology 2025年 238卷 109-118页

作者： Liu, Rui Liu, Xiao Wu, Lihong Du, Changlong Lv, Haiming Wan, Gengping Xiong, Hualin Yuan, Xiang Wang, Jieping Wang, Guizhen Institute of Electromagnetic Protection Materials and Spectral Innovation Technology State Key Laboratory of Tropic Ocean Engineering Materials and Materials Evaluation School of Materials Science and Engineering Hainan University Haikou570228 China Center for New Pharmaceutical Development and Testing of Haikou Center for Advanced Studies in Precision Instruments Haikou570228 China Key Laboratory of Pico Electron Microscopy of Hainan Province Center for Advanced Studies in Precision Instruments Haikou570228 China

electromagnetic wave (EMW) absorbers with anti-corrosion property are highly desired to enhance the durability of military targets in harsh condition. Herein, cross-link NiAl-layered double hydroxide (NiAl-LDH) nanosheets on the inner/outer surfaces of carbon microtubes (CMTs) are ingeniously constructed through the combination of atomic layer deposition technique and a hydrothermal method. The obtained NiAl-LDH/CMT composite exhibits excellent EMW absorption and corrosion resistance performance. The large internal cavity of CMT significantly enhances impedance matching. The uniform distribution of NiAl-LDH nanosheets on both the inner and outer surfaces of CMT generates numerous heterogeneous interfaces that induce substantial polarization loss. Consequently, at a filler rate of only 5 wt.%, the NiAl-LDH/CMT composite exhibits a minimum reflection loss of −60.2 dB and a maximum effective absorption bandwidth of 5.9 GHz. In addition, the combined high impermeability of CMT and the effective Cl−-trapping ability of NiAl-LDH endows NiAl-LDH/CMT composite with outstanding corrosion protection property in simulated seawater environment. Furthermore, the PO43− anions are effectively incorporated into the NiAl-LDH interlayer via anion exchange, which can further enhance corrosion protection capacity through surface inactivation from slow-release PO43− anions without reducing their EMW absorption performance. In summary, this work can give guidance for the development of efficient anti-corrosion EMW absorption materials. © 2025

关键词： Anodic protection

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A Novel High Torque Density Spoke-Array Permanent Magnets Vernier Machine with Magnets Bridge

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IEEE Transactions on Industry Applications 2025年

作者： Zhang, Yuwei Zhao, Yu Li, Dawei Qu, Ronghai Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

In recent years, permanent magnet vernier machine (PMVM) has drawn more attention due to their high torque density. To further improve torque capability, Spoke-array (SA) PM having better flux focusing effect are applied. However, SAPMVM suffers from a considerable torque reduction due to the deteriorated low order working flux harmonics caused by flux barrier effect. Especially, the higher pole ratio (PR), i.e., the ratio of PM pole-pair to armature pole-pair, the severer torque drop of SAPMVM. In this paper, a novel SAPMVM is proposed, where the magnets bridge is introduced, which can effectively restrict the flux barrier effect. As a result, both the working flux harmonics and torque density of SAPMVM are enhanced. To analyze the operating principle of proposed SAPMVM with magnets bridge, an equivalent magnet circuit model is established. Moreover, the electromagnetic performances of the proposed SAPMVM are compared with regular SAPMVM by FEA, where the torque of proposed SAPMVM has increased by 43.3% and 175.6% under rated-load when the PR is selected as 5 and 11. © 1972-2012 IEEE.

关键词： Permanent magnets

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Regional Short-Term Wind Power Prediction Based on CEEMDAN-FTC Feature Mapping and EC-TCN-BiLSTM Deep Learning

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Wind Energy 2025年第6期28卷

作者： Qin, Guoyuan Peng, Xiaosheng Yang, Zimin State Key Laboratory of Advanced Electromagnetic Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

Regional-scale holistic wind power prediction (WPP) is pivotal to securing the safety, stability, and economic efficiency of power systems. To improve the accuracy of regional short-term WPP, a method based on complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN), fine-to-coarse (FTC) feature mapping, and error compensation-temporal convolutional network-bidirectional Long short-term memory network (EC-TCN-BiLSTM) is proposed in this paper. First, the regional input features, encompassing data from numerous wind farms, are decomposed using the CEEMDAN algorithm to extract intrinsic mode functions (IMFs) and residuals at different time scales. Second, the decomposed IMFs and residuals are reconstructed using the adaptive FTC feature mapping technique, forming a high-dimensional feature set in the time-frequency domain, which boasts fewer features than the original set, thus diminishing the computational intricacy of the prediction model. Third, by combining the strengths of TCN and BiLSTM neural networks, the temporal and spatial correlations of input features can be captured effectively. Fourth, the integration of the EC module corrects the systematic errors of the prediction results, thereby further improving the prediction accuracy. Finally, case studies elucidate the efficacy of the proposed WPP method, illustrating a 0.41%–2.4% diminution in 24-h-ahead root mean square error (RMSE) and a 0.68%–2.63% reduction in 96-h-ahead RMSE relative to conventional methodologies. © 2025 The Author(s). Wind Energy published by John Wiley & Sons Ltd.

关键词： Convolutional neural networks

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Coordinated Control Strategy for Multi Hybrid Active Power Filters

Coordinated Control Strategy for Multi Hybrid Active Power F...

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2025 International Conference on Electrical Automation and Artificial Intelligence, ICEAAI 2025

作者： Wang, Chen Yang, Bo Wu, Yutong Li, Mingshu Li, Xingyang Yin, Jingyuan State Grid Beijing Electric Power Company Beijing China Institute of Electrical Engineering Chinese Academy of Sciences Beijing China Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology Qilu Zhongke Jinan China Shandong Key Laboratory of Advanced Electromagnetic Conversion Technology Jinan China

ISBN: (纸本)9798331506797

With the development of new power systems and power electronics technology, the power system in the 'double high' scenario faces certain challenges in harmonic control. To achieve precise real-time control of harmonics, this article proposes a collaborative control strategy for multi hybrid active power filters (HAPF). Based on Silicon Carbide Metal-Oxide-Semiconductor Field-Effect Transistor (SiC-MOSFET) novel power components, a modular HAPF was constructed, the active and passive parts were connected through coupling inductance to output effective compensation current. To achieve real-time and accurate detection of harmonics, an adaptive filter is constructed by combining Least Mean Square (LMS) and Least Mean Squared (LMF) method, and adaptively update the weight step size based on the error results. A coupling evaluation index was constructed by introducing the relative gain matrix (RGA), considering the compensation performance, capacity allocation, and coupling effects of each HAPF, the optimal allocation of compensation current for each device is determined. The simulation results showed that the proposed method can accurately detect and compensate for system harmonics through collaborative control of multiple HAPF, thereby improving the power quality of the power system. © 2025 IEEE.

关键词： Adaptive harmonic detection Cooperative Control HAPF Harmonic compensation RGA

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Hierarchical NiFe LDH/N-doped Co/nickel foam as highly active oxygen evolution reaction electrode for anion exchange membrane water electrolysis

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Nano Research 2025年第2期18卷 280-289页

作者： Jiansheng Wang Yongsheng Wang Xiaoxuan Guo Mengting Chen Jinjie Fang Xiaojie Li Wei Zhu Zhongbin Zhuang State Key Lab of Organic-Inorganic Composites and Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100029China Beijing Key Laboratory of Energy Environmental Catalysis Beijing University of Chemical TechnologyBeijing 100029China PetroChina Shenzhen New Energy Research Institute Co. Ltd.Shenzhen 518054China

Anion exchange membrane water electrolyzers(AEMWEs)are emerging as a promising technology due to the high performance and low ***,the development of highly active and stable non-precious metal-based catalysts for the anodic oxygen evolution reaction(OER)remains a great *** this study,we present a top-down construction strategy for anode design,resulting in a hierarchical NiFe layered double hydroxide(LDH)/N-doped Co/nickel foam(NF)electrode synthesized via a hydrothermal-gas phase nitridation–electrodeposition *** electrode features NiFe LDH nanoplates grown on N-doped Co nanowires supported by nickel foam *** NiFe LDH/N-doped Co/NF electrode demonstrates exceptional performance,achieving a current density of 100 mA·cm^(-2) at a low overpotential of 262 mV with minimal attenuation of just 7 mV NiFe LDH/N-doped Co/NF RuO_(2)/NF NiFe LDH/N-doped Co/NF after 100 h of *** assembled into an AEMWE,the system requires only 1.63 V to achieve a current density of 1 A·cm^(-2),surpassing the performance of most reported *** N-doped Co nanowires are shown to enhance both activity and stability by increasing the electrode’s surface area and reinforcing the catalyst–support interaction.

关键词： water electrolysis oxygen evolution reaction hierarchical structure synergistic effect

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Dielectric Mechanism and Spectrum Prediction Model for Insulating Paper Based on Three-Dimensional Frequency-Domain Spectroscopy

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IEEE Transactions on Dielectrics and Electrical Insulation 2025年

作者： Liu, Ruiqi Wang, Shengkang Lin, Fuchang Li, Hua Ministry of Education State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Wuhan430074 China

Moisture is a serious concern for transformers, as it will degrade insulation properties and accelerate aging. The dielectric mechanisms of oil-immersed paper (OIP) and the influence of moisture still remains contentious in existing studies, which prevents the application of Frequency-Domain Spectroscopy (FDS) technology in moisture assessment of transformers. OIP is a biphasic composite material composed of oil and paper, and the existence of oil would complicate the understanding of the dielectric mechanisms in solid insulation. Therefore, this study focuses on investigating the dielectric properties of non-immersed insulating paper using FDS. Firstly, the spectra of paper with different moisture content were analyzed, and the relationship between dielectric parameters and moisture was quantified through the proposed dielectric model of insulating paper. Then, a three-dimensional dielectric model for spectrum prediction was established, and the feasibility and universality of model was verified. Results show three distinct dielectric response processes in insulating papers: the hopping conduction (RI), the low-frequency relaxation polarization (RII), and the high-frequency relaxation polarization (RIII). With increasing moisture content, RI and RII processes shift synchronously and exponentially towards higher frequencies with the dielectric curve shape maintained, while RIII process is unaffected. Moreover, the proposed spectrum prediction model can accurately predict the spectrum of insulating paper with varying moisture content. The dielectric response mechanism and three-dimensional dielectric model of insulating paper identified in this study provide the theoretical basis and data support for subsequent studies of the dielectric mechanism and moisture assessment of oil-immersed paper. © 1994-2012 IEEE.

关键词： Frequency domain analysis

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Study on Double Feedforward Control Strategy for Three-Level Buck-Boost Bi-Directional Converter Applied in Energy-Storage Inverters 11th

Study on Double Feedforward Control Strategy for Three-Level...

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11th Frontier Academic Forum of Electrical engineering, FAFEE 2024

作者： Zhou, Chijun Fang, Yu Chen, Jie Li, Rui Shu, Kaixin Wang, Xuehua College of Information Engineering Yang Zhou University Yang Zhou China College of Electrical Energy and Power Engineering Yang Zhou University Yang Zhou China The State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9789819788156

This paper focuses on the three-level Buck-Boost Bi-directional converter (TL Buck-Boost BDC) applied in energy-storage inverters serving as charging or discharging circuit for storage battery. Based on the traditional dual closed-loop control method, a dual feedforward control strategy based on the balanced duty cycle signal at the midpoint of the direct current bus (DC Bus) and the battery voltage duty cycle signal is proposed. The balanced duty cycle signal at the midpoint of the DC Bus is generated by the balanced feedforward generator, and the battery voltage duty cycle signal is generated by the battery voltage feedforward generator. These two duty cycle signals are superimposed with the duty cycle signal generated by the dual closed-loop control to construct the duty cycle signal used to control the switching on or off of the switches in the TL Buck-Boost BDC, thereby achieving stable control of the charging or discharging operation in the energy-storage inverter while ensuring the DC-Bus voltage, Realized DC-Bus midpoint balance and improving the dynamic response speed of the system. The control parameters of the TL Buck-Boost BDC is designed, and the correctness and reliability of the method studied in this paper is verified by experimental results. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Buck converter

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