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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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Structural and Luminescent Properties of Mg_(0.25-x)Al_(2.57)O_(3.79)N_(0.21):xMn^(2+)Green-Emitting Transparent Ceramic Phosphor

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Journal of Wuhan University of technology(Materials Science) 2024年第3期39卷 533-540页

作者：郝留成 MIAO Xiaojun LI Kai ZHONG Jianying 涂兵田 YANG Zhangfu 王皓 Pinggao Group Co. LtdPingdingshan 467001China State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Hubei Longzhong Laboratory Xiangyang 430070China School of Materials Science and Engineering Anhui University of Science and TechnologyHuainan 232001China

A series of spinel-type Mg_(0.25-x)Al_(2.57)O_(3.79)N_(0.21):xMn^(2+)(MgAlON:xMn^(2+))phosphors were synthesized by the solid-state reaction *** transparent ceramic phosphors were fabricated by pressureless sintering followed by hot-isostatic pressing(HIP).The crystal structure,luminescence and mechanical properties of the samples were systematically *** transparent ceramic phosphors with tetrahedrally coordinated Mn^(2+)show strong green emission centered around 515 nm under blue light *** the Mn^(2+)concentration increases,the crystal lattice expands slightly,resulting in a variation of crystal field and a slight red-shift of green emission *** weak absorption peaks in the transmittance spectra originate from the spin-forbidden ^(4)T_(1)(^(4)G)→^(6)A_(1) transition of Mn^(2+).The decay time was found to decrease from 5.66 to 5.16 ms with the Mn^(2+)*** present study contributes to the systematic understanding of crystal structure and properties of MgAlON:xMn^(2+)green-emitting transparent ceramic phosphor which has a potential application in high-power light-emitting diodes.

关键词： transparent ceramic phosphor green emission MgAlON photoluminescence

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SHAP Algorithm for Transparent Power System Transient Stability Assessment: Critical Impact Factors Identification

SHAP Algorithm for Transparent Power System Transient Stabil...

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2023 International Conference on Power System technology, PowerCon 2023

作者： Lan, Yutian Shi, Zhongtuo Yao, Wei Zhou, Rui Luo, Feng Wen, Jinyu Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan China State Grid Electric Power Research Institute Nari Group Corporation Nanjing China

ISBN: (纸本)9798350300222

Data-driven power system transient stability assessment (TSA) is a promising way to improve both the prediction efficiency and precision, but 'black-box' property affects their reliability and hinders the extraction of knowledge from the model, such as the critical impact factors for transient stability. By developing a TSA model based on imbalance-XGBoost algorithm, it can enhance the identification of unstable samples and increase the reliability of the model. By employing SHAP algorithm, a fast calculation method of Shapley value, to the TSA model, it can achieve the best possible computation of how each feature affects the prediction result. By examining the feature contribution from both local and global aspects, it can thoroughly explore the critical impact factors and offer guidance for power system control. The experiment on the standard 39-bus test system demonstrates that SHAP algorithm can enhance the model interpretability and realize outstanding transient stability assessment by using the obtained critical impact factors. © 2023 IEEE.

关键词： Machine learning

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Phase Delay Analysis of SP-SECE for Piezoelectric Vibration Energy Harvesting and Optimization 10

Phase Delay Analysis of SP-SECE for Piezoelectric Vibration ...

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10th IEEE International Power Electronics and Motion Control Conference, IPEMC 2024 ECCE Asia

作者： Lv, Xinyue Peng, Han Lei, Junhao Zhao, Yidong Yan, Yuyao Huazhong University of Science and Technology China-EU Institute for Clean and Renewable Energy Wuhan China Huazhong University of Science and Technology School of Electrical and Electronic Engineering State Key Laboratory of Advanced Electromagnetic Technology Wuhan China

ISBN: (纸本)9798350351330

Synchronous charge extraction (SECE) have been a hot topic in piezoelectric energy harvesting. Some scholars have been using discrete electronic components to realize self-powered SECE. However, the SP-SECE has an obvious delay, which has a side effect on piezoelectric energy harvesting. In this paper, the delay of the SP-SECE circuit is specifically modeled. The influence of envelope detector and different piezoelectric patch parameters on delay is newly considered. The results of the analysis can provide more detailed guidelines for circuit design. © 2024 IEEE.

关键词： Energy harvesting

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Bidirectionally aligned MXene hybrid aerogels assembled with MXene nanosheets and microgels for supercapacitors

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Rare Metals 2023年第4期42卷 1249-1260页

作者： Pei-Xuan Li Guo-Zhen Guan Xin Shi Lei Lu Yu-Chao Fan Jie Xu Yuan-Yuan Shang Ying-Jiu Zhang Jin-Quan Wei Feng-Mei Guo Key Laboratory of Material Physics Ministry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou450052China Key Lab for Advanced Materials Processing Technology of Education Ministry State Key Lab of New Ceramic and Fine ProcessingSchool of Materials Science and EngineeringTsinghua UniversityBeijing100084China

MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface ***,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene *** is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the *** this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying *** bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport *** A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.

关键词： MXene MXene microgels Bidirectionally aligned structure Electrodes Supercapacitors

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Variable-frequency Multi-phase-shift Control Strategy for Wide-range Bidirectional Resonant Converter Considering Detuning 3

Variable-frequency Multi-phase-shift Control Strategy for Wi...

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3rd IEEE China International Youth Conference on Electrical engineering, CIYCEE 2022

作者： Han, Dongtong Chen, Chansong Dong, Mingyang Xu, Zhiwen Gan, Lin Zhang, Jingyue State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology China

ISBN: (数字)9781665477321

ISBN: (纸本)9781665477321

The CLLLC resonant converter naturally has symmetrical bidirectional power transmission characteristics due to its symmetrical circuit structure, but the transmission power and efficiency will be reduced when resonant network is detuned. In this paper, a mathematical model for the CLLLC resonant converter is established based on the first harmonic approximation(FHA) method. Then, a variable-frequency multi-phase-shift control strategy that can achieve bidirectional power transfer over a wide voltage range and reduce the adverse effects of detuning of the resonant network is proposed. Finally, through simulations and experiments, the proposed control strategy is proved to be able to reduce the adverse effect of detuning. © 2022 IEEE.

关键词： Energy transfer

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Synthesis of a novel Al foam with a periodic architecture by introducing hollow Al tubes and Al/Mg powders

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Journal of Materials Science & technology 2023年第17期148卷 105-115页

作者： Zhigang Xu Dayong Shen Kai Wang Peng He Jian Zhang Hao Zhang Peng Cao Shangyu Huang Jian Peng Qiang Shen Chuanbin Wang Lianmeng Zhang Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China State Key Lab of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Wuhan Second Ship Design and Research Institute Wuhan 430205China Department of Chemical and Materials Engineering University of AucklandPrivate Bag 92019Auckland 1142New Zealand

In this work,we synthesized a brand-new Al foam with a periodic structure via a simple powder metallurgical *** periodic architecture consists of both hierarchical porous and bi-directional composition-graded *** results show that the hierarchical porous material includes large pores on millimeter scale inheriting from the hollow structure of the Al tubes,and small pores on mi-crometer scale produced by the sintering of Al/Mg *** bi-directional Mg concentration-graded structure is formed in the tube walls due to the condensation of Mg vapor in the inner tube *** addition of Mg powders achieves excellent metallurgical bonding between the Al powders and the hollow tubes at 550℃.The plateau stress and energy absorption capacity of the Al foam in y-axis compression are significantly higher than that in the x-axis due to their anisotropic *** general,the Al foam with Mg addition presents the most superior compression performance,and we believe that our find-ings could open up a unique strategy for developing high-performance metallic foams with the periodic architecture involving both hierarchical porous and bi-directional graded structure.

关键词： Al foam Hollow Al tube Mg evaporation Bi-directional composition-graded structure Compression properties Energy absorbing performance

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Optimized Design and Analysis of Clip Bonding Packaging for Avalanche Bipolar Junction Transistor 2

Optimized Design and Analysis of Clip Bonding Packaging for ...

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2nd IEEE International Power Electronics and Application Symposium, PEAS 2023

作者： Xu, Mosai Liang, Lin Yan, Xiaoxue School of Electrical and Electronic Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Technology Engineering Research Center of Power Safety and Efficiency Ministry of Education Wuhan China

ISBN: (纸本)9798350313765

To meet the increasing demand for high switch speed of avalanche bipolar junction transistors (ABJT) and to solve the heat dissipation problem of the commonly used SOT23 packaging, an optimized packaging design for ABJT using the clip bonding is proposed. In this paper, a series of analysis is conducted based on finite element simulation to study the thermomechanical performance of the novel clip bonding packaging. A comparison of the parasitic parameters, thermal and mechanical properties between clip bonding and wire bonding packaging demonstrates that the bigger bonding area leads to lower inductances and thermal resistance, as well as better heat dissipation performance and reliability. The thickness of the copper sheet is also optimized and the reliability analysis is conducted using the Hallberg-Peck model, demonstrating that the reliability of the clip bonding packaging is superior to the conventional SOT23 packaging using wire bonding. © 2023 IEEE.

关键词： avalanche bipolar junction transistors clip bonding finite element analysis thermal resistance

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Milestones, hotspots and trends in the development of electric machines

iEnergy

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iEnergy 2022年第1期1卷 82-99页

作者： Ronghai Qu You Zhou Dawei Li State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology430074 WuhanChina School of Electrical and Electronic Engineering Nanyang Technological Uni-versity639798Singapore

As one of the greatest inventions of human beings,the electric machine(EM)has realized the mutual conversion between electrical energy and mechanical energy,which has essentially led humanity into the age of electrification and greatly promoted the progress and development of human *** paper will briefly review the development of EMs in the past two centuries,highlighting the historical milestones and investigating the driving force behind *** the innovation of theory,the progress of materials and the breakthrough of computer science and power electronic devices,the mainstream EM types has been continuously changing since its *** paper will not only summarize the basic operation principle and performance characteristics of traditional EMs,but also that of the emerging types of ***,control and drive system,as a nonnegligible part of EM system,will be complementarily ***,due to the background of global emission reduction,industrial intelligentization and transportation electrification,EM industry will usher again in a golden period of ***,several foreseeable future developing trends will be analyzed and summarized.

关键词： Electric machine(EM) historical review industrial applications research hotspot technology development topology

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A Fast Line Reclosing Strategy for Power System Under DG Access 4

A Fast Line Reclosing Strategy for Power System Under DG Acc...

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4th International Conference on Power engineering, ICPE 2023

作者： Pan, Wulue Xu, Feng Zhang, Zanzan Ma, Ruizhi Qian, Zhengxu Qiu, Yutao Chen, Shuiyao Fang, Yudong State Grid Zhejiang Electric Power Co. Ltd. Hangzhou China Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan China

ISBN: (纸本)9798350340020

For the automatic reclosing of power system under renewable energy source access, the current practice is usually to cut off the renewable energy source or block the reclosing gate after a fault occurs. This will lead to the shutdown of the renewable energy source and the interruption of power supply to a large number of local loads, which is not conducive to the safe operation of the grid and the efficient utilization of the renewable energy source. In this paper, a fast reclosing method is proposed for substation lines with inverter-type renewable energy source access, which can ensure the power supply of important loads and make the renewable energy source stable during the reclosing period without going off-grid. Firstly, it is pointed out that the inverter-type renewable energy source is switched to VSG-control during the reclosing period, so that it has the basic islanding operation capability. Then the method of load shedding with the startup of unloading resistor during the reclosing period is proposed to ensure the power balance between the new energy power and the loads. Next, adjusting the rated frequency of the renewable energy source to accelerate the simultaneous process, which can speed up the whole reclosing process. Finally, the simulations under different working conditions are carried out on the PSCAD/EMTDC to verify the feasibility of the proposed reclosing strategy. © 2023 IEEE.

关键词： Electric load shedding

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