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arXiv 2022年

作者： Liu, Mengqi Xia, Shuang Wan, Wenjian Qin, Jun Li, Hua Zhao, Changying Bi, Lei Qiu, Cheng-Wei Institute of Engineering Thermophysics MOE Key Laboratory for Power Machinery and Engineering School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China Department of Electrical and Computer Engineering National University of Singapore Singapore117583 Singapore National Engineering Research Center of Electromagnetic Radiation Control Materials University of Electronic Science and Technology of China Chengdu610054 China State Key Laboratory of Electronic Thin-Films and Integrated Devices University of Electronic Science and Technology of China Chengdu610054 China Key Laboratory of Terahertz Solid State Technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai2000509 China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Science Beijing1000049 China

Spectral/angular emissivity e and absorptivity α of an object are widely believed to be identical by Kirchhoff's law of thermal radiation in reciprocal systems, but this introduces an intrinsic and inevitable energy loss for energy conversion and harvesting devices. So far, experimental evidences of breaking this well-known balance are still absent, and previous theoretical proposals are restricted to narrow single-band nonreciprocal radiation. Here we observe for the first time, to our knowledge, the violation of Kirchhoff's law using ultrathin (0.6 has been experimentally demonstrated under a moderate external magnetic field. Moreover, based on magnetized ENZ building blocks supporting asymmetrically radiative Berreman and surface ENZ modes, we show versatile shaping of nonreciprocal thermal radiation: single-band, dual-band, and broadband nonreciprocal emission spectra at different wavebands. Our findings of breaking Kirchhoff's law will advance the conventional understanding of emission and absorption processes of natural objects, and lay a solid foundation for more comprehensive studies in designing various nonreciprocal thermal emitters. The reported recipe of diversely shaping nonreciprocal emission will also breed new possibilities in renovating next-generation nonreciprocal energy devices in the areas of solar cells, thermophotovoltaic, radiative cooling, etc. Copyright © 2022, The Authors. All rights reserved.

关键词： III-V semiconductors

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A Review of Metal Powder-CO2 Propulsion technology

A Review of Metal Powder-CO2 Propulsion Technology

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International Conference on Vision, Image and Signal Processing (ICVISP)

作者： Hanxiao Wu Kun Cai Haiwang Li Tiantong Xu Weidong Fang Wenbin Wang Pengpeng Nie National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang University Beijing People’s Republic of China School of Energy and Power Engineering Beihang University Beijing People’s Republic of China ShenYuan Honors College of Beihang University Beihang University Beijing People’s Republic of China Beijing Institute of Control Engineering Space Propulsion Product Development Center Beijing People’s Republic of China Research Institute of Aero-Engine Beihang University Beijing People’s Republic of China

ISBN: (纸本)9781665408356

With the advancement of Mars exploration and deep space exploration technology, the metal powder-CO! rocket engine suitable for the Martian atmosphere has received more and more attention from scholars. In this paper, we summarized some researches about power-CO 2 propulsion technology, including the combustion mechanism studies and pivotal technologies. Then, we pointed out some potential research directions in the future.

关键词： Temperature distribution Mars Powders Metals Ignition Combustion Temperature control

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Condition evaluation method of wind turbine based on real-time reliability

Condition evaluation method of wind turbine based on real-ti...

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2019 International Conference on Sensing, Diagnostics, Prognostics, and control, SDPC 2019

作者： He, Chengbing Ma, Li Wang, Runze Li, Xiaobo Jiao, Xiaofeng Song, Lei North China Electric Power University School of Energy Power and Mechanical Engineering Beijing China Inner Mongolia Electric Power Science Research Institute Inner Mongolia Hohhot China Chinese Academy of Sciences Technology and Engineering Center for Space Utilization Line Beijing China

ISBN: (纸本)9781728101996

With the rapid development of wind power generation worldwide, the condition evaluation of wind turbine has received more and more attention. In this paper, wind turbine is divided into three levels: component level, device level, and subsystem level, and the system of condition evaluation is constructed. The real-time reliability analysis model of wind turbine is proposed. The real-time reliability reduction is calculated from component level, equipment level and subsystem level in turn by using variable weight synthesis method. Finally, the condition evaluation of wind turbine is realized. The validity of this method is verified by a case analysis. The research results in this paper can provide decision-making assistance for the management of daily operation and maintenance of wind turbines and improve the operational efficiency of wind farms. © 2019 IEEE.

关键词： Wind turbines

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research on fault diagnosis method based on FMEA/FTA and bayesian network

Research on fault diagnosis method based on FMEA/FTA and bay...

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2019 International Conference on Sensing, Diagnostics, Prognostics, and control, SDPC 2019

作者： He, Chengbing Wang, Runze Ma, Li Li, Xiaobo Jiao, Xiaofeng Song, Lei North China Electric Power University School of Energy Power and Mechanical Engineering Beijing China Inner Mongolia Electric Power Science Research Institute Inner Mongolia Hohhot China Chinese Academy of Sciences Technology and Engineering Center for Space Utilization Line Beijing China

ISBN: (纸本)9781728101996

The construction of Bayesian network (BN) model is a bottleneck problem that needs to be solved urgently in the field of fault diagnosis. Combining failure mode and effect analysis(FMEA) and fault tree analysis(FTA) can solve this problem well. In this paper, a BN model based on FMEA/FTA is proposed. The transformation methods of FMEA to BN and FTA to BN are analyzed. The structural matrix is used to realize the information transformation. The noisy-max model is used to determine the BN parameters. Taking the rub-impact fault between the high pressure rotor and the front shaft seal of a 600 MW turbogenerator unit as an example, the application of the BN model based on FMEA/FTA in fault diagnosis is realized from three aspects which are BN model construction, prior probability and conditional probability assignment, and diagnosis reasoning, respectively. © 2019 IEEE.

关键词： Bayesian networks

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research on damping addition and vibration reduction technology of frame aerospace electronic chassis

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Journal of Physics: Conference Series 2021年第1期1754卷

作者： Zhang yu Zhang bolin Beijing Satellite Manufacturing Co. LTD Beijing Space Power Supply Transformation and Control Engineering Research Center Beijing 100080 China

This paper poses a box instrumentation in aerospace electronic chassis TO-5 encapsulation relay under the action of impact environmental load state of reverse fault mode, by reasonable single frames of viscoelastic damping materials added, increasing box style structure between the PCB mechanical installation interface damping ratio and frequency ratio, finally realizes the transfer rate is reduced, achieve instrumentation relay PCB, lower impact acceleration response. By adding damping cushion to the frame machine installation interface, the load transfer path of impact mechanics is optimized to reduce the installation stiffness and change the fundamental frequency characteristics of the whole machine.

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Coordinated control strategy of a DC grid with energy storage system

Coordinated control strategy of a DC grid with energy storag...

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作者： Yang, Bo Sang, Bingyu Yang, Zhihan Li, Menbo Xiang, Wang Lu, Xiaojun Yao, Liangzhong Tao, Yibin School of Electrical Engineering Southeast University Nanjing China State Key Laboratory of Operation and Control of Renewable Energy ＆ Storage Systems China Electric Power Research Institute Beijing China China Electric Power Research Institute Nanjing China Jiangsu Engineering Technology Research Center for Energy Storage Conversion and Application China Electric Power Research Institute Nanjing China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

DC grid has a prospect of application in collecting and transmitting large-scale renewable energy over long distance. However, the randomness and fluctuation of the renewable power may hamper the stable operation of DC grid. Energy storage device is able to actively absorb or supplement active power, which can be used to smooth the power fluctuation. The paper investigates a DC grid topology with energy storage and proposes a coordinated control strategy. The proposed strategy enables coordinated control of the renewable energy output power, pumped storage power and the grid consuming power. During the steady state, the control strategy enables the system DC voltage stable and power flow of the grid under zero-error control. During the faulted time, the coordinate control strategy enables the converter fast response and maintains the system DC voltage within safety margin. The effectiveness of the coordinated control strategy is verified by simulation in PSCAD/ EMTDC. © 2019 Institution of engineering and *** right reserved.

关键词： Energy storage

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Construction of an example system for AC/DC hybrid power grid with high-proportion renewable energy

Construction of an example system for AC/DC hybrid power gri...

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作者： Zhao, Dawei Ma, Jin Qian, Minhui Zhu, Lingzhi Yao, Liangzhong Ding, Kun Han, Hualing State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Changping District Beijing China State Key Laboratory of Operation and Control of Renewable Energy and Storage Systems Jiangsu Engineering Technology Research Center for Energy Storage Conversion and Application China Electric Power Research Institute Gulou District Nanjing China Wind Power Technology Center of Gansu Electric Power Company Qilihe District Lanzhou China

Large-scale wind and solar power generations have got rapid development in recent years in China and abroad. They always connect to load centres through high-voltage direct current (HVDC) transmission or ultra HVDC (UHVDC) transmission lines. Such systems are so large and it is necessary to make appropriate equivalence according to the purpose of different research. At present, the analysis model of this kind of real system is few, and simplified single-machine infinite-bus system or IEEE example system is adopted most of the time, which may affect the accuracy of analysis results. Here, the UHVDC project from a practical renewable energy base to load centres in China is chosen as an example, the actual structure and parameters are used to establish a typical example system for AC/DC hybrid power grid with high-proportion renewable energy. The new-generation synchronous condenser with large capacity and the supporting synchronous generators are all considered. First, the installed power generation, power grid structure, and load configuration of example system are introduced. Then the load flow distribution and transient stability characteristics are analysed by using DIgSILENT powerFactory software. Finally, the feasibility of the proposed example system is shown by simulation results. © 2019 Institution of engineering and *** right reserved.

关键词： Electric load flow

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Einstein Probe discovery of EP240408a: a peculiar X-ray transient with an intermediate timescale

arXiv

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arXiv 2024年

作者： Zhang, Wenda Yuan, Weimin Ling, Zhixing Chen, Yong Rea, Nanda Rau, Arne Cai, Zhiming Cheng, Huaqing Zelati, Francesco Coti Dai, Lixin Hu, Jingwei Jia, Shumei Jin, Chichuan Li, Dongyue O'Brien, Paul Shen, Rongfeng Shu, Xinwen Sun, Shengli Sun, Xiaojin Wang, Xiaofeng Yang, Lei Zhang, Bing Zhang, Chen Zhang, Shuang-Nan Zhang, Yonghe An, Jie Buckley, David Coleiro, Alexis Cordier, Bertrand Dou, Liming Eyles-Ferris, Rob Fan, Zhou Feng, Hua Fu, Shaoyu Fynbo, Johan P.U. Galbany, Lluis Jha, Saurabh W. Jiang, Shuaiqing Kong, Albert Kuulkers, Erik Lei, Weihua Li, Wenxiong Liu, Bifang Liu, Mingjun Liu, Xing Liu, Yuan Liu, Zhu Maitra, Chandreyee Marino, Alessio Monageng, Itumeleng Nandra, Kirpal Sanders, Jeremy Soria, Roberto Tao, Lian Wang, Junfeng Wang, Song Wang, Tinggui Wang, Zhongxiang Wu, Qingwen Wu, Xuefeng Xu, Dong Xu, Yanjun Xue, Suijian Xue, Yongquan Zhang, Zijian Zhu, Zipei Zou, Hu Bao, Congying Chen, Fansheng Chen, Houlei Chen, Tianxiang Chen, Wei Chen, Yehai Chen, Yifan Cui, Chenzhou Cui, Weiwei Dai, Yanfeng Fan, Dongwei Guan, Ju Han, Dawei Hou, Dongjie Hu, Haibo Huang, Maohai Huo, Jia Jia, Zhenqing Jiang, Bowen Jin, Ge Li, Chengkui Li, Junfei Li, Longhui Li, Maoshun Li, Wei Li, Zhengda Lian, Tianying Liu, Congzhan Liu, Heyang Liu, Huaqiu Lu, Fangjun Luo, Laidan Ma, Jia Mao, Xuan Pan, Haiwu Pan, Xin Song, Liming Sun, Hui Tan, Yunyin Tang, Qingjun Tao, Yihan Wang, Hao Wang, Juan Wang, Lei Wang, Wenxin Wang, Yilong Wang, Yusa Wu, Qinyu Xu, Haitao Xu, Jingjing Xu, Xinpeng Xu, Yunfei Xu, Zhao Xue, Changbin Xue, Yulong Yan, Ailiang Yang, Haonan Yang, Xiongtao Yang, Yanji Zhang, Juan Zhang, Mo Zhang, Wenjie Zhang, Zhen Zhang, Zhen Zhang, Ziliang Zhao, Donghua Zhao, Haisheng Zhao, Xiaofan Zhao, Zijian Zhou, Hongyan Zhou, Yilin Zhu, Yuxuan Zhu, Zhencai National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China School of Astronomy and Space Sciences University of Chinese Academy of Sciences Beijing100049 China Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China CSIC BarcelonaE-08193 Spain BarcelonaE-08034 Spain Max Planck Institute for Extraterrestrial Physics Garching85748 Germany Innovation Academy for Microsatellites Chinese Academy of Sciences Shanghai201210 China Department of Physics University of Hong Kong Hong Kong School of Physics and Astronomy University of Leicester LeicesterLE1 7RH United Kingdom School of Physics and Astronomy Sun Yat-Sen University Zhuhai519082 China Department of Physics Anhui Normal University Wuhu241002 China Shanghai Institute of Technical Physics Chinese Academy of Sciences Shanghai200083 China Physics Department Tsinghua University Beijing100084 China Nevada Center for Astrophysics University of Nevada Las Vegas Las VegasNV89154 United States Department of Physics and Astronomy University of Nevada Las Vegas Las VegasNV89154 United States South African Astronomical Observatory Cape Town7935 South Africa Department of Astronomy University of Cape Town Rondebosch7701 South Africa Department of Physics University of the Free State Bloemfontein9300 South Africa Université Paris Cité CNRS Astroparticule et Cosmologie ParisF-75013 France Université Paris Cité CEA Paris-Saclay IRFU DAp-AIM Gif-sur-Yvette91191 France Department of Astronomy Guangzhou University Guangzhou510006 China Copenhagen2200 Denmark Niels Bohr Institute University of Copenhagen Copenhagen2200 Denmark Department of Physics and Astronomy Rutgers the State University of New Jersey PiscatawayNJ08854-8019 United States Institute for Cosmic Ray Research The University of Tokyo Kashiwa277-8582 Japan ESA ESTEC Noordwijk2201 AZ Netherlands Department of Astronomy Schoo

We report the discovery of a peculiar X-ray transient, EP240408a, by Einstein Probe (EP) and follow-up studies made with EP, Swift, NICER, GROND, ATCA and other ground-based multiwavelength telescopes. The new transient was first detected with Wide-field X-ray Telescope (WXT) on board EP on April 8th, 2024, manifested in an intense yet brief X-ray flare lasting for 12 seconds. The flare reached a peak flux of 3.9 × 10−9 erg cm−2 s−1 in 0.5-4 keV, ∼300 times brighter than the underlying X-ray emission detected throughout the observation. Rapid and more precise follow-up observations by EP/FXT, Swift and NICER confirmed the finding of this new transient. Its X-ray spectrum is non-thermal in 0.5-10 keV, with a power-law photon index varying within 1.8-2.5. The X-ray light curve shows a plateau lasting for ∼4 days, followed by a steep decay till becoming undetectable ∼10 days after the initial detection. Based on its temporal property and constraints from previous EP observations, an unusual timescale in the range of 7-23 days is found for EP240408a, which is intermediate between the commonly found fast and long-term transients. No counterparts have been found in optical and near-infrared, with the earliest observation at 17 hours after the initial X-ray detection, suggestive of intrinsically weak emission in these bands. We demonstrate that the remarkable properties of EP240408a are inconsistent with any of the transient types known so far, by comparison with, in particular, jetted tidal disruption events, gamma-ray bursts, X-ray binaries and fast blue optical transients. The nature of EP240408a thus remains an enigma. We suggest that EP240408a may represent a new type of transients with intermediate timescales of the order of ∼10 days. The detection and follow-ups of more of such objects are essential for revealing their origin. © 2024, CC BY-NC-ND.

关键词： Infrared devices

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Modified Porous Membrane with High Solar-to-Thermal conversion and Oil Resistance Performance for Solar Steam Generation

SSRN

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SSRN 2022年

作者： Gao, Fang He, Bin Zou, Guangxin Wang, Yi Wang, Yi Zhao, Xiaoli Shen, Yanjun School of Environment Science and Engineering Guangdong University of Technology Guangzhou510006 China Institute of Eco-Environmental and Soil Sciences Guangdong Academy of Sciences Guangzhou510650 China Guangdong-Hong Kong-acao Joint Laboratory for Environmental Pollution and Control Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou510640 China College of New Energy North China Electric Power University Beijing102206 China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental Sciences Beijing100012 China CAS Key Laboratory of Agricultural Water Resources Hebei Key Laboratory of Water Saving Agriculture Center for Agricultural Resources Research IGDB Chinese Academy of Sciences Shijiazhuang050021 China School of Advanced Agricultural Sciences University of The Chinese Academy of Sciences Beijing100049 China

The utilization of solar steam generator via photothermal conversion is a sustainable and highly sufficient solution for addressing long-standing water scarcity. Due to its extensive optical absorption, dopamine has been considered as a promising thermal-heat conversion material. In this work, by co-depositing Fe 3+ and 3-glycidyloxypropyltrimethoxysilane (KH550) with polydopamine (PDA), a high-performance, low-cost, and scalable modified membrane (called PVDF/PDA@KH550@Fe 3+ ) with superior oil resistance was developed. Under one sun illumination, the resulting PVDF/PDA@KH550@Fe 3+ membrane generated solar steam with a high efficiency of 90.33% and a high evaporation rate of 1.40 kg·m -2 ·h -1 . More importantly, the evaporation rate still performs well even in oil-contaminated water due to the improvement of hydrophilicity and anti-fouling capabilities of the modified membrane. In oil-in-water emulsion, the evaporation rate approaches 1.33 kg·m -2 ·h -1 and the evaporation efficiency reaches 85.49%. This study demonstrated that solar steam generation using PVDF/PDA@KH550@Fe 3+ membrane could be a viable option for seawater and oily wastewater purification. © 2022, The Authors. All rights reserved.

关键词： Oil resistance

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Selective CO2Reduction to Ethylene Mediated by Adaptive Small-molecule engineering of Copper-based Electrocatalysts

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Angewandte Chemie 2023年第50期135卷

作者： Dr. Shenghua Chen Dr. Chengliang Ye Dr. Ziwei Wang Dr. Peng Li Dr. Wenjun Jiang Dr. Zechao Zhuang Dr. Jiexin Zhu Dr. Xiaobo Zheng Dr. Shahid Zaman Dr. Honghui Ou Lei Lv Dr. Lin Tan Dr. Yaqiong Su Dr. Jiang Ouyang Prof. Dingsheng Wang National Innovation Platform (Center) for Industry-Education Integration of Energy Storage Technology School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an 710049 P. R. China Engineering Research Center of Advanced Rare Earth Materials Department of Chemistry Tsinghua University Beijing 100084 P. R. China School of Chemistry Xi'an Key Laboratory of Sustainable Energy Materials Chemistry State Key Laboratory of Electrical Insulation and Power Equipment Engineering Research Center of Energy Storage Materials and Devices Ministry of Education Xi'an Jiaotong University Xi'an 710049 P. R. China Qian Xuesen Laboratory of Space Technology China Academy of Space Technology Beijing 100094 P. R. China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing International School of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 P. R China Key Laboratory of Energy Conversion and Storage Technologies Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen 518055 P. R. China School of Biomedical Engineering Guangzhou Medical University Guangzhou 511436 P. R. China

Electrochemical CO 2 reduction reaction (CO 2 RR) over Cu catalysts exhibits enormous potential for efficiently converting CO 2 to ethylene (C 2 H 4 ). However, achieving high C 2 H 4 selectivity remains a considerable challenge due to the propensity of Cu catalysts to undergo structural reconstruction during CO 2 RR. Herein, we report an in situ molecule modification strategy that involves tannic acid (TA) molecules adaptive regulating the reconstruction of a Cu-based material to a pathway that facilitates CO 2 reduction to C 2 H 4 products. An excellent Faraday efficiency (FE) of 63.6 % on C 2 H 4 with a current density of 497.2 mA cm −2 in flow cell was achieved, about 6.5 times higher than the pristine Cu catalyst which mainly produce CH 4 . The in situ X-ray absorption spectroscopy and Raman studies reveal that the hydroxyl group in TA stabilizes Cu δ+ during the CO 2 RR. Furthermore, theoretical calculations demonstrate that the Cu δ+ /Cu 0 interfaces lower the activation energy barrier for *CO dimerization, and hydroxyl species stabilize the *COH intermediate via hydrogen bonding, thereby promoting C 2 H 4 production. Such molecule engineering modulated electronic structure provides a promising strategy to achieve highly selective CO 2 reduction to value-added chemicals.

关键词： C2H4 CO2RR Cuδ+/Cu0 Hydrogen Bonding TA Molecule

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