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Nonlinear optical response of BiVO4 and its application for ultrafast pulsed fiber lasers

Optics Express 2025年第3期33卷 6559-6566页

作者： Du, Ruonan Shi, Aokun Lian, Yudong Fang, Huajing Qi, Yaoyao Bai, Zhenxu Wang, Yulei Huang, Feng Ding, Jie Lu, Zhiwei Center for Advanced Laser Technology Hebei University of Technology Tianjin300401 China Hebei Key Laboratory of Advanced Laser Technology and Equipment Tianjin300401 China State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University Xi’an710049 China College of Mechanical Engineering and Automation Fuzhou University Fuzhou350108 China

Herein, we present aN Er-doped all-fiber laser with BiVO4 as the saturable absorber (SA). To illustrate the nonlinear optical response, a two-dimensional model of monoclinic and its electronic structure was calculated. The nonlinear absorption properties were evaluated utilizing the Z-scan technique, and a saturable absorber was fabricated for integration into a fiber laser, resulting in a stable Q-switched output. At a maximum pump power of 600 mW, the fiber laser achieved an average output power of 25.23 mW and a pulse energy of 330.76 nJ. This research confirms that BiVO4 material exhibits outstanding nonlinear optical characteristics, thereby broadening its scope of application in the realm of ultrafast pulsed fiber lasers. © 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement.

关键词： Optical depth

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Design and Analysis of Coupled Self-charging Mechanical DC Circuit Breaker

Design and Analysis of Coupled Self-charging Mechanical DC C...

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International Conference of Electrical, Electronic and Networked Energy Systems, EENES 2024

作者： Xie, Yunlong Yuan, Zhao Chen, Lixue State Key Laboratory of Advanced Electromagnetic Technology Huazhong University of Science and Technology Wuhan430074 China Key Laboratory of Pulsed Power Technology Ministry of Education School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9789819620456

Mechanical DC circuit breakers have become an irreplaceable part of flexible DC power grids because of their advantages of high economy, low con-duction impedance, and reliable control. However, the large volume of the charging circuit and the high interruption pressure in low current are still the problems it faces. To address the aforementioned issues, a Coupled Self-charging Mechanical DC Circuit Breaker (CSC-DCCB) is proposed. This innovative solution mitigates the risk of switch arc reignition during the commutation process by incorporating a self-charging circuit. The energy consumption process of metal-oxide varistor will cause the capacitor to complete recharging, and this voltage will be used for the reclosing of the CSC-DCCB. Secondly, the parameter of the CSC-DCCB is optimized to achieve a lower overall capacity of the circuit breaker and the rated voltage of the converter switches, which retains the traditional low conduction loss. Finally, the feasibility of CSC-DCCB is validated through PSCAD, the technical parameters of CSC-DCCB are compared with traditional DCCB, showing that CSC-DCCB has better economic efficiency. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Flexible electronics

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Effect of electrochemical hydrogen charging on the microstructure and mechanical behavior of a duplex structured Mg-8wt.%Li alloy

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Journal of Magnesium and Alloys 2025年第2期13卷 668-680页

作者： Shuo Wang Daokui Xu Baojie Wang Dongliang Wang Zhiqiang Zhang Li Liu Jie Chen Key Lab of Electromagnetic Processing of Materials Ministry of EducationNortheastern UniversityShenyang110819China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China Engineering Research Center of Advanced Materials Preparing Technology Ministry of EducationNortheastern UniversityShenyang110819China Binzhou Institute of Technology BinzhouShandong Province256606China Shandong Key Laboratory of Advanced Aluminium Materials and Technology BinzhouShandong Province256606China School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang110159China Spallation Neutron Source Science Center Dongguan523803China

In this work,through performing microstructural characterization,tensile testing and failure analysis,the influence of electrochemical hydrogen charging on the microstructure and mechanical behavior of an as-cast Mg-8wt.%Li alloy was *** revealed that after being hydrogen charged at 50 mA/cm2 for respectively 3 h,6 h and 18 h in 0.1 M NaCl solution,obvious HID occurred and the damage degree was gradually increased with the hydrogen charging *** the sample being hydrogen charged for 3 h,micro pores with the diameter ranging from 10~30µm were formed and preferentially present inα-Mg ***,micro cracks with the length ranging from 10~50µm mainly initiated inα-Mg phase,atα-Mg/β-Li interfaces and the peripheries of *** the increase of hydrogen charging time,the numbers of pores and cracks were obviously *** results revealed that the hydrogen charging can simultaneously decrease the tensile strength and ductility of the *** with the uncharged sample,the tensile yield strength,ultimate tensile strength and the elongation ratio to failure were respectively reduced by 5.7%,7.3%,31.7%for the 3h-charged sample and 24.6%,24.8%,67.0%for the 18h-charged *** analysis indicated that hydrogen charging can induce the brittle cracking of the alloy and the size of brittle cracking region being composed of quasi-cleavage facets and interfacial cracks on the fracture surfaces was increased with the hydrogen charging time.

关键词： Magnesium-lithium alloy Microstructure Hydrogen-induced damage Hydrogen embrittlement Mechanical behavior

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Strength and toughness mechanism of single Ti microalloyed steels

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Journal of Iron and Steel Research International 2025年第3期32卷 769-782页

作者： Yi Wang Zhi-chao Che Yu-feng Chen Shu-feng Yang Jun-fen Zhang Qi-he Xue School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing100083China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China HBIS Group Chengde Steel Company Chengde067000HebeiChina

The mechanism of strength and toughness variation in Ti microalloyed steel within the range of 0.04–0.157 wt.%was *** adding 0.13 wt.%Ti,the steel achieves higher strength while maintaining a certain level of elongation and low-temperature impact *** increasing Ti content,the grain size in the steel decreased from 17.7 to 8.9μ*** decrease in grain size is accompanied by an increase in the percentage of low-angle grain boundaries and dislocations,which act as barriers to hinder crack *** Ti microalloyed steel exhibits a 20%increase in yield strength and a 14%increase in tensile *** transformation of steel plasticity occurs when the Ti content exceeds 0.102 wt.%.The low-temperature impact toughness of the steel gradually decreases with increasing Ti *** low Ti content,the low-temperature impact toughness is reduced due to crack initiation by large-size *** high Ti content,the low-temperature impact toughness of the steel deteriorates due to several *** include the narrower tough–brittle transition zone,grain boundary embrittlement caused by small-sized grains,and the decrease in the solid solution strengthening effect.

关键词： Ti microalloyed steel Second phase Tensile property Low-temperature impact property Strengthening mechanism

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Role of iron ore in enhancing gasification of iron coke:Structural evolution,influence mechanism and kinetic analysis

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 58-69页

作者： Jie Wang Wei Wang Xuheng Chen Junfang Bao Qiuyue Hao Heng Zheng Runsheng Xu School of Chemistry and Materials Science Hubei Engineering UniversityXiaogan 432000China Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081China Institue of Ironmaking Technology Baosteel Central Research InstituteShanghai 201999China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The utilization of iron coke provides a green pathway for low-carbon *** uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the microstructure of iron coke was ***,a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric *** findings indicate that compared to coke,iron coke exhibits an augmentation in micropores and specific surface area,and the micropores further extend and *** provides more adsorption sites for CO_(2) molecules during the gasification process,resulting in a reduction in the initial gasification temperature of iron *** the heating rate in non-isothermal gasification can enhance the reactivity of iron *** metallic iron reduced from iron ore is embedded in the carbon matrix,reducing the orderliness of the carbon structure,which is primarily responsible for the heightened reactivity of the carbon *** kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore ***,as the proportion of iron ore increases,the activation energy for the carbon gasification gradually decreases,from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.

关键词： low-carbon ironmaking iron coke gasification structural evolution kinetic model

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Integrating Friction Noise for In Situ Monitoring of Polymer Wear Performance: A Machine Learning Approach in Tribology

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Journal of Tribology 2025年第6期147卷 061701页

作者： Chen, Shengshan Cheng, Ganlin Guo, Fei Jia, Xiaohong Wen, Xiaohao State Key Laboratory of Tribology in Advanced Equipment Tsinghua University Beijing100084 China Macau Institute of Systems Engineering Macau University of Science and Technology 999078 China

Friction and wear between mating surfaces significantly affect the efficiency and performance of mechanical systems. Traditional tribological research relies on post-observation methods, limiting the understanding of dynamic friction behavior. In contrast, in situ monitoring provides real-time insights into evolving friction dynamics. This study employs machine learning to monitor polymer wear performance through friction noise. The predictive accuracy of various machine learning methods, including Extremely Randomized Trees, Gradient-Boosting Decision Trees, AdaBoost, LightGBM, Deep Forest, and Deep Neural Networks, is compared for wear-type classification. Additionally, the LSBoost regression is selected as the optimal method for predicting polymer wear-rates across various temperatures. The results underscore the potential of using friction noise and machine learning for real-time wear monitoring, offering valuable insights for tribological system maintenance and failure prediction. © 2024 by ASME.

关键词： Tribology

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Synergistic enhancement of alkaline hydrogen evolution reaction by role of Ni-Fe LDH introducing frustrated Lewis pairs via vacancy-engineered

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Chinese Chemical Letters 2025年第3期36卷 512-516页

作者： Mianfeng Li Haozhi Wang Zijun Yang Zexiang Yin Yuan Liu Yingmei Bian Yang Wang Xuerong Zheng Yida Deng State Key Laboratory of Marine Resource Utilization in South China Sea School of Materials Science and EngineeringHainan UniversityHaikou 570228China Tianjin Key Laboratory of Composite and Functional Materials Key Laboratory of Advanced Ceramics and Machining Technology(Ministry of Education)School of Materials Science and EngineeringTianjin UniversityTianjin 300072China

The alkaline hydrogen evolution reaction(HER)is a crucial process for sustainable hydrogen production,yet it requires efficient and stable electrocatalysts to overcome the high activation energy *** article discusses a novel strategy for enhancing the performance of Ni-Fe layered double hydroxide(Ni-Fe LDH)in the alkaline HER by modifying it with a frustrated Lewis acid-base pair(FLP)constructed through vacancy *** study found that the modified Ni-Fe LDH exhibited improved alkaline HER *** functional theory(DFT)calculations demonstrate that the introduction of FLP can activate water and protons more efficiently than monometallic sites,thus reducing the alkaline HER energy barrier and *** HER under alkaline conditions,the Volmer step involves an additional hydrolysis dissociation compared to acidic conditions,which is one of the factors contributing to the slow reaction *** paper demonstrates that FLPs can alter the rate-determining step in alkaline HER from the Volmer step to a step with a lower energy barrier,more suitable for hydrogen *** work provides new insights into the role of FLPs in regulating the mechanism and kinetics of HER and opens a new direction for the design and optimization of LDH-based and other electrocatalysts.

关键词： Ni-Fe LDH Frustrated Lewis acid-base pair Density functional theory The ab initio molecular dynamics The alkaline hydrogen evolution reaction

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Passive on-chip isolators based on the thin-film lithium niobate platform

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Chinese Physics B 2025年第3期34卷 408-413页

作者： Jiacheng Liu Gongyu Xia Qilin Hong Pingyu Zhu Kai-Kai Zhang keyu Xia Ping Xu Shiqiao Qin Zhihong Zhu College of Advanced Interdisciplinary Studies&Hunan Provincial Key Laboratory of Novel Nano Optoelectronic Information Materials and Devices National University of Defense TechnologyChangsha 410073China Institute for Quantum Information and State Key Laboratory of High-Performance Computing College of Computer Science and TechnologyNational University of Defense TechnologyChangsha 410073China College of Engineering and Applied Sciences National Laboratory of Solid State Microstructuresand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210023China

Optical isolators,the photonic analogs of electronic diodes,are essential for ensuring the unidirectional flow of light in optical systems,thereby mitigating the destabilizing effects of back ***-film lithium niobate(TFLN),hailed as“the silicon of photonics,”has emerged as a pivotal material in the realm of chip-scale nonlinear optics,propelling the demand for compact optical *** report a breakthrough in the development of a fully passive,integrated optical isolator on the TFLN platform,leveraging the Kerr effect to achieve an impressive 10.3 dB of isolation with a minimal insertion loss of 1.87 *** theoretical simulations have demonstrated that our design,when applied to a microring resonator with a Q factor of 5×10^(6),can achieve 20 dB of isolation with an input power of merely 8 *** advancement underscores the immense potential of lithium niobate-based Kerr-effect isolators in propelling the integration and application of high-performance on-chip lasers,heralding a new era in integrated photonics.

关键词： thin-film lithium niobate Kerr effect optical isolator

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Hierarchical hollow microspheres assembled from carbon nanosheets integrated with molybdenum carbide nanoparticles for boosting microwave absorption properties

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Nano Research 2025年第1期18卷 10-20页

作者： Zongsheng Chen Yahui Wang Yi Liu Zhigang Li Xiangyin Lv Liping Liu Yajing Chang Jiaming Shi Xiao Zhang State Key Laboratory of Pulsed Power Laser Technology School of Electronic EngineeringNational University of Defense TechnologyHefei 230037China Anhui Provincial Laboratory of Advanced Laser Technology School of Electronic EngineeringNational University of Defense TechnologyHefei 230037China Centre for Environmental and Energy Nanomaterials Anhui Key Laboratory of Nanomaterials and NanotechnologyCAS Centre for Excellence in NanoscienceInstitute of Solid State PhysicsHefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China

Hierarchical hollow structure has demonstrated potential for enhancing electromagnetic(EM)attenuation and improving impedance matching,garnering significant attention for ***,we have successfully implemented compositional and structural engineering to fabricate hollow Mo2C/C microspheres with controllable composition by coupling interaction between dopamine hydrochloride and ammonium *** the synergistic effect of composition and hollow structure,the strongest reflection loss intensity and broadest effective absorption of the optimized sample reach-70.2 dB and 6.2 GHz,*** formation of hollow heterogeneous structures not only favors impedance matching feature,but also generates considerable contribution to EM attenuation ***,radar cross-section simulation data indicate that hollow Mo2C/C microspheres with compositional optimization and heterogeneous structures have broad prospects for practical applications.

关键词： electromagnetic absorption Mo2C/C microwave absorption hollow structure

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Numerical Study of the Current Density on the Armature and Rail Interface with Dynamic Contact

Numerical Study of the Current Density on the Armature and R...

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International Conference of Electrical, Electronic and Networked Energy Systems, EENES 2024

作者： Xu, Jinghan Xia, Shengguo Chen, Lixue Ministry of Education Hubei Wuhan430074 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Wuhan430074 China School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China

ISBN: (纸本)9789819620791

The electrical contact between the armature and rail is acknowledged as imperfect electrical contact (ImPEC), exhibiting characteristics distinct from bulk behavior. It is important to understand the current distribution of the ImPEC for future design and optimization. This paper proposes ImPEC boundary conditions by combining the contact layer model (CLM) and the Cooper-Mikic-Yoranovich model (CMYM), and the current distribution is numerically studied. Variations in the contact pressure and current density with time are analyzed. The results show a rapid increase in the contact pressure and area during the current ramp-up stage, being constant in the flat stage, and a gradual decline in the current ramp-down stage. The current path changes with the contact area, and the current shifts from the trailing edge to the leading edge over time. Additionally, comparative calculations are performed to analyze current variations under dynamic contact. Results suggest that the current distribution is influenced by magnetic diffusion and forced shifts of current caused by dynamic contact. © Beijing Paike Culture Commu. Co., Ltd. 2025.

关键词： Threshold current density

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