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Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of technology (Transportation Science and engineering) 2005年第2期29卷 190-193页

作者： Yin, Qizhi Xiao, Jinsheng Zhao, Zaili Yang, Bo Sch. of Energy and Power Engineering Wuhan Univ. of Technol. Wuhan 430063 China State Key Lab. of Advanced Technology for Materials Synthesis and Processing Wuhan Univ. of Technol. Wuhan 430072 China

The transient temperature field analysis aims at the thermal response of LPG vessel under pool fire surrounding environment. The finite element analysis method is used to calculate the temperature field. The thermal boundary conditions of LPG vessel are determined according to heat transfer theory and calculated by the software PLGS99. The results show that the maximum temperature gradient of vessel appears near the highest surface where the liquid can reach, and fluctuation of liquid surface is the main reason of high temperature gradient.

关键词： Finite element analysis Liquefied petroleum gas Pressure vessel Temperature field

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Observation of anomalous π modes in photonic Floquet engineering

arXiv

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arXiv 2018年

作者： Cheng, Qingqing Pan, Yiming Wang, Huaiqiang Zhang, Chaoshi Yu, Dong Gover, Avi Zhang, Haijun Li, Tao Zhou, Lei Zhu, Shining Shanghai Key Lab of Modern Optical System and Engineering Research Center of Optical Instrument and System Ministry of Education University of Shanghai for Science and Technology Shanghai200093 China Department of Electrical Engineering Physical Electronics Tel Aviv University Ramat Aviv69978 Israel National Laboratory of Solid State Microstructures School of Physics Nanjing University Nanjing210093 China National Laboratory of Solid State Microstructures School of Physics and Collaborative Innovation Centre of Advanced Microstructure Nanjing University Nanjing210093 China State Key Laboratory of Surface Physics Key Laboratory of Micro and Nano Photonic Structures Ministry of Education Physics Department Fudan University Shanghai200433 China National Laboratory of Solid State Microstructures School of Physics College of Engineering and Applied Sciences Nanjing University Nanjing210093 China

Recent progresses on Floquet topological phases have shed new light on time-dependant quantum systems, among which one-dimensional (1D) Floquet systems have been under extensive theoretical research. However, an unambiguous experimental observation of these 1D Floquet topological phases has still been lacking. Here, by periodically bending ultrathin metallic arrays of coupled corrugated waveguides, a photonic Floquet simulator was well designed and successfully fabricated to simulate the periodically driven Su-Schrieffer-Heeger model. Intriguingly, under moderate driven frequencies, we first experimentally observed and theoretically verified the Floquet topological π mode propagating along the array's boundary. The different evolutionary behaviors between static and non-static topological end modes have also been clearly demonstrated. Our experiment also reveals the universal high-frequency behavior in perically driven systems. We emphasize that, our system can serve as a powerful and versatile testing ground for various phenomena related to time-dependant 1D quantum phases, such as Thouless charge pumping and manybody localization. Copyright © 2018, The Authors. All rights reserved.

关键词： Quantum optics

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Electrical Behavior against Current Impulse in ZnO Varistor Ceramics with SiO2 Addition

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Journal of Physics: Conference Series 2020年第1期1637卷

作者： Bowen Wang Zhen Fang Zhiyao Fu Yongjing Peng State Key Laboratory of Disaster Prevention & Reduction for Power Grid Transmission and Distribution Equipment State Grid Hunan Electric Power Company Disaster Prevention and Reduction Center Changsha410129 China. State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 Hubei China

SiO2 addition effect on electrical behaviour against current impulse in the ZnO varistors was investigated. SiO2 acts as a controller in ZnO grain growth, decreasing the grain size of ZnO from 8.87 to 5.86 μm, which in turn results in an increase in breakdown voltage E1mA from 192.77 to 252.57 V/mm. SiO2 has a significant influence on the current energy withstand capability and impulse aging characteristics. The results indicated that the SiO2 content was optimized at 1.5 mol%, exhibiting the best energy withstand capability of 332.03J/cm3 and clamping ratio of 1.71.

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Critical roles of edge turbulent transport in the formation of high-field-side high-density front and density limit disruption in J-TEXT tokamak

arXiv

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arXiv 2023年

作者： Shi, Peng Wang, Yuhan Gao, Li Sun, Hongjuan Yang, Qinghu Xu, Xin Shen, Chengshuo Chen, Yanqiu Tao, Qinlin Chen, Zhipeng Wu, Haosheng Wang, Lu Chen, Zhongyong Wang, Nengchao Yang, Zhoujun Li, Jingchun Ding, Yonghua Pan, Yuan United Kingdom Atomic Energy Authority Culham Centre for Fusion Energy Culham Science Centre Abingdon OxonOX14 3DB United Kingdom International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Southwestern Institute of Physics PO Box 432 Chengdu610041 China NEMO Group Dipartmento Energia Politecnico di Torino Corso Duca degli Abruzzi 24 Torino10129 Italy Department of Earth and Space Sciences Southern University of Science and Technology Shenzhen518055 China

This article presents an in-depth study of the sequence of events leading to density limit disruption in J-TEXT tokamak plasmas, with an emphasis on boudary turbulent transport and the high-field-side high-density (HFSHD) front. These phenomena were extensively investigated by using Langmuir probe and Polarimeter-interferometer diagnostics. The research reveals a consistent pattern of events as the plasma density ramps up: the collapse of the sheared radial electric field, the enhancement of a boundary broadband turbulence (50~80kHz), the increase of boundary particle transport induced by this turbulence, edge cooling and the emergence of the HFSHD front. These phenomena occur once the plasma density exceeds a critical value. Importantly, by exploring plasmas with varying edge safety factor (qα), it’s revealed that the density thresholds for these phenomena are all inversely proportional to qα. The findings offer valuable insights into the mechanisms underlying density limit disruptions in tokamak plasmas, suggesting that the enhancement of edge turbulent transport plays crucial roles in the edge cooling and triggering the HFSHD front. For the first time, a strong link between the edge turbulent transport and the HFSHD front has been observed. In addition, the evolution of boundary electron temperature across various qα plasmas can further validate the link between the edge turbulent transport and the HFSHD formation. © 2023, CC BY-NC-ND.

关键词： Plasma density

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Observation of Negative Terahertz Photoconductivity in Large Area Type-II Dirac Semimetal PtTe2

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Physical Review Letters 2021年第22期126卷 227402-227402页

作者： Peng Suo Huiyun Zhang Shengnan Yan Wenjie Zhang Jibo Fu Xian Lin Song Hao Zuanming Jin Yuping Zhang Chao Zhang Feng Miao Shi-Jun Liang Guohong Ma Department of Physics Shanghai University Shanghai 200444 China College of Electronics and Information Engineering Shandong University of Science and Technology Qingdao 266590 China Institute of Brain-inspired Intelligence National Laboratory of Solid State Microstructures School of Physics Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing 210093 China Terahertz Technology Innovation Research Institute Terahertz Spectrum and Imaging Technology Cooperative Innovation Center Shanghai Key Lab of Modern Optical System University of Shanghai for Science and Technology 516 JunGong Road Shanghai 200093 China STU & SIOM Joint Laboratory for Superintense Lasers and the Applications Shanghai 201210 China School of Physics University of Wollongong Wollongong New South Wales 2522 Australia

As a newly emergent type-II Dirac semimetal, platinum telluride (PtTe2) stands out from other two dimensional noble-transition-metal dichalcogenides for the unique band structure and novel physical properties, and has been studied extensively. However, the ultrafast response of low energy quasiparticle excitation in terahertz frequency remains nearly unexplored yet. Herein, we employ optical pump-terahertz probe (OPTP) spectroscopy to systematically study the photocarrier dynamics of PtTe2 thin films with varying pump fluence, temperature, and film thickness. Upon photoexcitation the terahertz photoconductivity (PC) of PtTe2 films shows abrupt increase initially, while the terahertz PC changes into negative value in a subpicosecond timescale, followed by a prolonged recovery process that lasted a few nanoseconds. The magnitude of both positive and negative terahertz PC response shows strongly pump fluence dependence. We assign the unusual negative terahertz PC to the formation of small polaron due to the strong electron-phonon (e−ph) coupling, which is further substantiated by temperature and film thickness dependent measurements. Moreover, our investigations give a subpicosecond timescale of simultaneous carrier cooling and polaron formation. The present study provides deep insights into the underlying dynamics evolution mechanisms of photocarrier in type-II Dirac semimetal upon photoexcitation, which is of crucial importance for designing PtTe2-based optoelectronic devices.

关键词： Photoinduced effect Polarons

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Doping-induced superconductivity in the topological semimetal Mo5Si3

arXiv

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arXiv 2020年

作者： Wu, Jifeng Hua, Chenqiang Liu, Bin Cui, Yanwei Zhu, Qinqing Xiao, Guorui Wu, Siqi Cao, Guanghan Lu, Yunhao Ren, Zhi School of Science Westlake University 18 Shilongshan Road Hangzhou310064 China Institute of Natural Sciences Westlake Institute for Advanced Study 18 Shilongshan Road Hangzhou310064 China Department of Physics Fudan University Shanghai200433 China Zhejiang Province Key Laboratory of Quantum Technology and Device Department of Physics Zhejiang University Hangzhou310027 China State Key Lab of Silicon Materials School of Materials Science and Engineering Zhejiang University Hangzhou310027 China

Chemical doping of topological materials may provide a possible route for realizing topological superconductivity. However, all such cases known so far are based on chalcogenides. Here we report the discovery of superconductivity induced by Re doping in the topological semimetal Mo5Si3 with a tetragonal structure. Partial substitution of Re for Mo in Mo5−xRexSi3 results in an anisotropic shrinkage of the unit cell up to the solubility limit of approximately x = 2. Over a wide doping range (0.5 ≤ x ≤ 2), these silicides are found to be weakly coupled superconductors with a fully isotropic gap. Tc increases monotonically with x from 1.67 K to 5.78 K, the latter of which is the highest among superconductors of the same structural type. This trend in Tc correlates well with the variation of the number of valence electrons, and is mainly ascribed to the enhancement of electron-phonon coupling. In addition, band structure calculations reveal that superconducting Mo5−xRexSi3 exhibits nontrivial band topology characterized by Z2 invariants (1;000) or (1;111) depending on the Re doping level. Our results suggest that transition metal silicides are a fertile ground for the exploration of candidate topological superconductors. Copyright © 2020, The Authors. All rights reserved.

关键词： Silicides

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Neuromorphic model-based neural decoders for brain-computer interfaces: a comparative study

Neuromorphic model-based neural decoders for brain-computer ...

引用

IEEE Biomedical Circuits and Systems (BIOCAS)

作者： Yijie Weng Yu Qi Yueming Wang Gang Pan College of Biomedical Engineering & Instrument Science Zhejiang University Hangzhou China MOE Frontier Science Center for Brain Science and Brain-Machine Integration Zhejiang University Hangzhou China College of Computer Science and Technology Zhejiang University Hangzhou China The State Key Lab of Brain-Machine Intelligence Zhejiang University Hangzhou China Qiushi Academy for Advanced Studies Zhejiang University Hangzhou China

ISBN: (数字)9798350354959

ISBN: (纸本)9798350354966

Brain-computer interfaces that convert neural signals into control commands for external devices have demonstrated great potential in neural rehabilitation. Most recently, the growing demand for developing large-scale brain signal recording devices has highlighted the need for power-efficient neural signal processing. Neuromorphic computing models, implemented with chips, can provide ultra-low-cost computation of neural signals, facilitating brain-implantable devices. In our work, we evaluated the neural decoding ability of neuromorphic models in comparison with traditional neural decoding approaches. We found that neuromorphic model-based neural decoders showed high accuracy comparable to existing decoders while with significantly lower computational costs. Our results suggest the potential of using neuromorphic models for highly efficient computing with large-scale brain data.

关键词： Neuromorphic engineering Computational modeling Biological system modeling Brain modeling Brain-computer interfaces Data models Decoding Recording Computational efficiency Integrated circuit modeling

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An improved optimal control strategy for hybrid AC/DC power system

引用

IOP Conference Series: Earth and Environmental Science 2018年第1期188卷

作者： C H Gao W M Liu T T Zheng Z W Liu S H Miao Y L Kang Z H Fan Y L Liu M M Zhang State Grid East Inner Mongolia Electric Power Company Limited Electric Power Research Institute Hohhot 010020 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Electric Power Security and High Efficiency Key Laboratory School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

The additional modulation function of high voltage direct current (HVDC) links can improve the system stability while the unavoidable random external disturbance and sudden changes seriously affect the controller performance and the system stability. In this paper, an improved control scheme based on inverse optimal adaptive control is proposed for the hybrid AC/DC system which considers the system parameter error, external disturbance and other random perturbation. The proposed control scheme combines the inverse optimal control approach and the adaptive control method to account for the modelling errors and uncertainty, which aims at the disturbance attenuation and the optimal operating of the hybrid AC/DC power system. Besides, the improved PI (Proportional-Integral) controller based on the lead-lag link for the current control of HVDC system is proposed to further improve system dynamic performance. Simulations conducted on a typical hybrid AC/DC system show the correctness and validity of the proposed control method.

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Coordinated control strategy of doubly fed wind power generation system under unbalanced grid voltage

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IOP Conference Series: Earth and Environmental Science 2018年第1期188卷

作者： C H Gao Y L Kang S H Miao Z W Liu Z H Fan Y L Liu W M Liu T T Zheng M M Zhang State Grid East Inner Mongolia Electric Power Company Limited Electric Power Research Institute Hohhot 010020 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Electric Power Security and High Efficiency Key Laboratory School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

A coordinated control method for doubly fed wind power generation system under unbalanced grid voltage is presented in this paper, which can remove the negative effects of unbalanced voltage on the doubly fed induction generator (DFIG) such as the unbalance of stator and rotor current. And the method can suppress the double frequency oscillations of the output active and reactive power. To improve the operating performance, the operation mechanism of DFIG system with a series grid side converter (SGSC) under unbalanced grid voltage is described firstly, and the strategy for series grid side converter aiming at maintaining the stator three phase voltage balance is proposed, and then the stator and rotor currents will keep balanced. Meanwhile, the mathematical model of the parallel grid side converter (PGSC) is analysed under unbalanced grid voltage and the double frequency power control equation is established. According to the control equation, a control strategy based on a proportional resonance (PR) power compensator for the parallel grid side converter is put forward, then the control goal of suppressing the double frequency oscillations of the output active and reactive power of the whole system simultaneously is accomplished, which improves the output quality of the system and ensures the safe operation of the connected grid. The proposed coordinated control strategy in this paper verified by the simulations of a doubly fed wind power generation system model built in PSCAD/EMTDC.

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Power system joint energy and reserve scheduling model considering variable speed pumped hydro storage for mitigating wind curtailment

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IOP Conference Series: Earth and Environmental Science 2019年第1期354卷

作者： T T Zheng Y W Li P W Yang X L Chen R Zheng S H Miao H Ji H R Yin State Grid East Inner Mongolia Electric Power Company Limited Electric Power Research Institute Hohhot 010020 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Hubei Electric Power Security and High Efficiency Key Laboratory School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

The large-scale integration of wind power brings great challenges to power system secure and economic operation. In order to address this challenge, the variable speed pump storage hydropower plant (VS-PSHP) technology and demand response technology have addressed a lot attention. In this paper, the coordination of the thermal power generator, the wind power plant, the VS-PSHP and multi-type flexible loads are considered, and a day-ahead and real-time coordinated scheduling model are proposed. The proposed model can formulate the generation, contingency reserve and power distribution factor schedules simultaneously. Numerical simulation results indicate that the coordination of VS-PSHP and multi-type flexible loads can increase the system operation economic and mitigating the wind power curtailment. The results also show that the VS-PSHP is good at providing contingency reserve, and the participation of VS-PSHP can lead to a relatively lower total system operation cost compared to the participation of fixed speed pump storage hydropower plant (FS-PSHP).

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