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Ultrabroadband,few-cycle pulses directly from a Mamyshev fiber oscillator

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Photonics Research 2020年第1期8卷 65-69页

作者： CHUNYANG MA ANKITA KHANOLKAR yimin zang ANDY CHONG Department of Electronic Science and Engineering Jilin UniversityChangchun 130012China Department of Physics University of DaytonDaytonOhio 45469USA Department of Electro-Optics and Photonics University of DaytonDaytonOhio 45469USA

While the performance of mode-locked fiber lasers has been improved significantly,the limited gain bandwidth restricts them from generating ultrashort pulses approaching a few cycles or even *** we present a novel method to achieve few-cycle pulses(~5 cycles)with an ultrabroad spectrum(~400 nm at-20 dB)from a Mamyshev oscillator configuration by inserting a highly nonlinear photonic crystal fiber and a dispersion delay line into the cavity.A dramatic intracavity spectral broadening can be stabilized by the unique nonlinear processes of a self-similar evolution as a nonlinear attractor in the gain fiber and a"perfect"saturable absorber action of the Mamyshev *** the best of our knowledge,this is the shortest pulse width and broadest spectrum directly generated from a fiber laser.

关键词： fiber oscillator cycle

Temporal manipulation of spatiotemporal optical vortices with an Airy pulse[Invited]

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Chinese Optics Letters 2023年第12期21卷 1-5页

作者： yimin zang Fanli Wei Hee Sung Kim Andy Chong Department of Electro-Optics and Photonics University of DaytonDaytonOhio 45469USA Department of Physics Pusan National UniversityBusan 46241Republic of Korea

We demonstrate the temporal manipulation of spatiotemporal optical vortices(STOVs)by utilizing Airy *** combining a STOV with an Airy temporal profile,the STOV exhibits nondispersive,self-accelerating,and self-healing... 详细信息

关键词： spatiotemporal vortex Airy pulse manipulation

Optimized the vanadium electrolyte with sulfate-phosphoric mixed acids to enhance the stable operation at high-temperature

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Frontiers of Chemical Science and Engineering 2024年第2期18卷 13-26页

作者： Ling Ge Tao Liu yimin Zhang Hong Liu School of Resource and Environmental Engineering Wuhan University of Science and TechnologyWuhan 430081China State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control Wuhan University of Science and TechnologyWuhan 430081China Hubei Collaborative Innovation Center for High Efficient Utilization of Vanadium Resources Wuhan University of Science and TechnologyWuhan 430081China Hubei Provincial Engineering Technology Research Center of High Efficient Cleaning Utilization for Shale Vanadium Resource Wuhan University of Science and TechnologyWuhan 430081China School of Resource and Environmental Engineering Wuhan University of TechnologyWuhan 430070China

Herein, the influence of the concentration design and comprehensive performance of the sulfate-phosphoric mixed acid system electrolyte is investigated to realize an electrolyte that maintains high energy density and stable operation at high temperatures. Static stability tests have shown that VOPO4 precipitation occurs only with vanadium(V) electrolyte. The concentration of vanadium ion of 2.0–2.2 mol·L^(–1), phosphoric acid of 0.10–0.15 mol·L^(–1), and sulfuric acid of 2.5–3.0 mol·L^(–1) are suitable for a vanadium redox flow battery in the temperature range from –20 to 50 ℃. The equations for predicting the viscosity and conductivity of electrolytes are obtained by the response surface method. The optimized electrolyte overcomes precipitation generation. It has 2.8 times higher energy density than the non-phosphate electrolyte, and a coulomb efficiency of 94.0% at 50 ℃. The sulfate-phosphoric mixed acid system electrolyte promotes the electrode reaction process, increases the current density, and reduces the resistance. This work systematically optimizes the concentrations of composition of positive and negative vanadium electrolytes with mixed sulfate-phosphoric acid. It provides a basis for the different valence states and comprehensive properties of sulfate-phosphoric mixed acid system vanadium electrolytes under extreme environments, guiding engineering applications.

关键词： all vanadium redox flow battery mixed-acid vanadium electrolyte concentration optimization response surface methodology high-temperature stability

Adaptive Robust Servo Control for Vertical Electric Stabilization System of Tank and Experimental Validation

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Defence Technology（防务技术） 2024年第1期31卷 326-342页

作者： Darui Lin Xiuye Wang yimin Wang Guolai Yang School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094China

A tracking stability control problem for the vertical electric stabilization system of moving tank based on adaptive robust servo control is *** paper mainly focuses on two types of possibly fast timevarying but bounded uncertainty within the vertical electric stabilization system:model parameter uncertainty and uncertain ***,the vertical electric stabilization system is constructed as an uncertain nonlinear dynamic system that can reflect the practical mechanics transfer process of the ***,the dynamical equation in the form of state space is established by designing the angular tracking ***,the comprehensive parameter of system uncertainty is designed to estimate the most conservative effects of ***,an adaptive robust servo control which can effectively handle the combined effects of complex nonlinearity and uncertainty is *** feasibility of the proposed control strategy under the practical physical condition is validated through the tests on the experimental *** paper pioneers the introduction of the internal nonlinearity and uncertainty of the vertical electric stabilization system into the settlement of the tracking stability control problem,and validates the advanced servo control strategy through experiment for the first time.

关键词： Adaptive robust servo control Experimental validation Nonlinearity compensation System uncertainty Vertical electric stabilization system

Logit prototype learning with active multimodal representation for robust open-set recognition

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Science China(Information Sciences) 2024年第6期67卷 297-312页

作者： yimin FU Zhunga LIU Zicheng WANG School of Automation Northwestern Polytechnical University

Robust open-set recognition(OSR) performance has become a prerequisite for pattern recognition systems in real-world applications. However, the existing OSR methods are primarily implemented on the basis of single-modal perception, and their performance is limited when single-modal data fail to provide sufficient descriptions of the objects. Although multimodal data can provide more comprehensive information than single-modal data, the learning of decision boundaries can be affected by the feature representation gap between different modalities. To effectively integrate multimodal data for robust OSR performance, we propose logit prototype learning(LPL) with active multimodal representation. In LPL, the input multimodal data are transformed into the logit space, enabling a direct exploration of intermodal correlations without the impact of scale inconsistency. Then, the fusion weights of each modality are determined using an entropybased uncertainty estimation method. This approach realizes adaptive adjustment of the fusion strategy to provide comprehensive descriptions in the presence of external disturbances. Moreover, the single-modal and multimodal representations are jointly optimized interactively to learn discriminative decision ***, a stepwise recognition rule is employed to reduce the misclassification risk and facilitate the distinction between known and unknown classes. Extensive experiments on three multimodal datasets have been done to demonstrate the effectiveness of the proposed method.

关键词： logit prototype learning multimodal perception open-set recognition uncertainty estimation

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Circulation Background and Genesis Mechanism of a Cold Vortex over the Tibetan Plateau during Late April 2018

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Advances in Atmospheric Sciences 2024年第6期41卷 1201-1216页

作者： Duming GAO Jiangyu MAO Guoxiong WU yimin LIU State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province Institute of Plateau MeteorologyChina Meteorological AdministrationChengdu 610072China Chinese Academy of Sciences Center for Excellence in Tibetan Plateau Earth Sciences Beijing 100101China

A cold vortex occurred over the northeastern Tibetan Plateau(TP)on 27 April 2018 and subsequently brought excessive rainfall to the spring farming area in southern China when moving *** study investigates the genesis mechanism of the cold TP vortex(TPV)by diagnosing reanalysis data and conducting numerical *** demonstrate that the cold TPV was generated in a highly baroclinic environment with significant contributions of positive potential vorticity(PV)forcing from the tropopause and diurnal thermodynamic impact from the *** a positive PV anomaly in the lower stratosphere moved towards the TP,the PV forcing at the tropopause pushed the tropospheric isentropic surfaces upward,forming isentropic-isplacement ascent and reducing static stability over the *** descent of the tropopause over the TP also produced a tropopause folding over the northeastern TP associated with a narrow high-PV column intruding downwards over the TPV genesis site,resulting in ascending air in the free ***,in conjunction with the descending air in the valley area during the night,produced air stretching just at the TPV genesis *** the surface cooling at night increased the surface static stability,the aforementioned vertical air-stretching thus converted the produced static stability to vertical ***,the cold TPV was generated over the valley at night.

关键词： tropopause PV forcing air column stretching static stability vertical vorticity

Coalbursts in China: Theory, practice and management

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 1-25页

作者： Yishan Pan yimin Song Hao Luo Yonghui Xiao Institute of Disaster Rock Mechanics Liaoning UniversityShenyang110036China School of Civil Engineering North China University of TechnologyBeijing100144China College of Computer Science Liaoning UniversityShenyang110036China School of Physics Liaoning UniversityShenyang110036China

Coalburst is one of the most serious disasters that threaten the safe production of coal mines, and this disaster is particularly serious in China. This paper presents an overview of coalbursts in China since 1980s. From the "stress and energy" and "regional and local" perspectives, the achievements in the theory, practice and management of coalbursts in China are systematically summarized. A theoretical system of coalbursts has been formed to reveal the deformational behavior of coalbursts and explain the mechanism of coalbursts. The occurrence conditions of coalbursts are put forward and the critical stress is obtained. The stress index method for risk evaluation of coalbursts before mining is proposed, and the deformation localization prediction method of coalbursts is put forward. The relationship between energy release and absorption in the process of coalbursts is found, and the prevention and control methods of coalbursts, including the regional method, the local method and support, are presented. The safety evaluation index of coalburst prevention and control is put forward. The integrated prevention and control method for coal and gas outbursts is proposed. The prevention and control technology and equipment of coalbursts have also been developed. Amongst them, the distribution law of the critical stress in China coalburst mines is discovered. The technology and equipment for monitoring, prevention and control of coalbursts, as well as for integrated prevention and control of combined coalbursts and other disasters, have been developed. The energy-absorbing and coalburst-preventing support technology for roadways is invented, and key engineering parameters of coalburst prevention and control are pointed out. In China, coalburst prevention and control laws and standards have been developed. Technical standards for coalbursts are formulated, statute and regulations for coal mines are established, and regulatory documents are promoted.

关键词： Coalbursts Rockbursts Dynamic disaster Energy-absorbing support Monitoring and early warning

A multichannel thermal bubble-actuated impedance flow cytometer with on-chip TIA based on CMOS-MEMS

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Journal of Semiconductors 2024年第5期45卷 41-49页

作者： Shengxun Cai Jianqing Nie Kun Wang yimin Guan Demeng Liu School of Microelectronics Shanghai UniversityShanghai 201800China Shanghai AURE Technology Limited Company Shanghai 201800China

Electrochemical impedance spectroscopy(EIS)flow cytometry offers the advantages of speed,affordability,and portability in cell analysis and cytometry ***,the integration challenges of microfluidic and EIS read-out circuits hinder the downsizing of cytometry *** address this,we developed a thermal-bubble-driven impedance flow cytometric application-specific integrated circuit(ASIC).The thermal-bubble micropump avoids external piping and equipment,enabling high-throughput *** a total of 36 cell counting channels,each measuring 884×220μm^(2),the chip significantly enhances the throughput of flow *** cell counting channel incorporates a differential trans-impedance amplifier(TIA)to amplify weak biosensing *** eliminating the parasitic parameters created at the complementary metal-oxidesemiconductor transistor(CMOS)-micro-electromechanical systems(MEMS)interface,the counting accuracy can be *** on-chip TIA can adjust feedback resistance from 5 to 60 kΩto accommodate solutions with different *** chip effectively classifies particles of varying sizes,demonstrated by the average peak voltages of 0.0529 and 0.4510 mV for 7 and 14μm polystyrene beads,***,the counting accuracies of the chip for polystyrene beads and MSTO-211H cells are both greater than 97.6%.The chip exhibits potential for impedance flow cytometer at low cost,high-throughput,and miniaturization for the application of point-of-care diagnostics.

关键词： EIS flow cytometry CMOS-MEMS thermal bubble lab-on-chip

Multi-locomotion transition of tensegrity mobile robot under different terrains

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Science China(Technological Sciences) 2024年第2期67卷 536-557页

作者： YANG Qi LIU XinYu WANG PanFeng SONG yimin SUN Tao Key Laboratory of Mechanism Theory and Equipment Design(Tianjin University) Ministry of EducationTianjin UniversityTianjin 300350China

Knowing how to make a multi-locomotion robot achieve locomotion transition under different terrains is a challenging problem,especially for tensegrity robots with multi-locomotion *** this study,a motion planning method for the transition of a multi-locomotion tensegrity robot(hereafter TJUBot)under different terrains is *** robot can achieve four locomotion modes:earthworm-like,inchworm-like,tumbling,and sliding locomotion with only two *** models of the four locomotion modes under five typical terrains,including flat ground,confined space,obstacle,gap,and descending slope,are established using the energy ***,the kinematic characteristics(driving law and initial position)of the robot under these terrains are *** this basis,motion planning for the locomotion transition of TJUBot is conducted,which includes a perception strategy based on three laser sensors and a transition strategy under different *** driving laws of the two motors that can ensure the effective locomotion transition of TJUBot under different terrains are naturally ***,experiments are *** demonstrate that the robot can achieve effective locomotion transition when the motion planning method is used.

关键词： multi-locomotion robot tensegrity kinematic modeling locomotion transition