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Identification of the optimal doping position of hetero-atoms in chalcogen-doped Fe-N-C catalysts for oxygen reduction reaction

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Particuology 2024年第6期89卷 99-108页

作者： Weihao Liu Huanhuan He Qingtao Liu Xin Wan Jianglan Shui School of Materials Science and Engineering Beihang UniversityBeijing100191China School of space and Environment Beihang UniversityBeijing102206China Tianmushan laboratory Hangzhou310023China

The excellent oxygen reduction reaction(ORR)activity of Fe–N–C catalysts in acidic media makes them potential for low-cost proton exchange membrane fuel *** recent years,it has been shown that heteroatoms(B,O,S,P,Cl,F,etc.)can be used as electron-withdrawing groups to modulate the planar structure and electron distribution of the Fe–Nx active sites to achieve simultaneous improvement of catalytic activity and ***,the optimal location of the heteroatoms remains ***,taking chalcogen heteroatoms(S and Se)as an example,we control the doping positions and investigate their effect on the ORR performance of the Fe–N–C *** first coordination shell of the iron single atom is identified as the optimal doping *** optimized catalysts Fe–N_(3)Se_(1)/NC and Fe–N_(3)Se_(1)/NC demonstrate improved activity and stability in both half cells and fuel *** work provides insights into the enhancement mechanism of heteroatom doping in single-atom catalysts.

关键词： Oxygen reduction reaction Fe-N-C catalysts Hetero-atom doping Doping position Enhancement mechanism

The Soft X-ray Imager(SXI)on the SMILE Mission

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Earth and Planetary Physics 2024年第1期8卷 5-14页

作者： S.Sembay A.L.Alme D.Agnolon T.Arnold A.Beardmore A.Belén Balado Margeli C.Bicknell C.Bouldin G.Branduardi-Raymont T.Crawford J.P.Breuer T.Buggey G.Butcher R.Canchal J.A.Carter A.Cheney Y.Collado-Vega H.Connor T.Crawford N.Eaton C.Feldman C.Forsyth T.Frantzen G.Galgóczi J.Garcia G.Y.Genov C.Gordillo H-P.Gröbelbauer M.Guedel Y.Guo M.Hailey D.Hall R.Hampson J.Hasiba O.Hetherington A.Holland S-Y.Hsieh M.W.J.Hubbard H.Jeszenszky M.Jones T.Kennedy K.Koch-Mehrin S.Kögl S.Krucker K.D.Kuntz C.Lakin G.Laky O.Lylund A.Martindale J.Miguel Mas Hesse R.Nakamura K.Oksavik N.Østgaard H.Ottacher R.Ottensamer C.Pagani S.Parsons P.Patel J.Pearson G.Peikert F.S.Porter T.Pouliantis B.H.Qureshi W.Raab G.Randal A.M.Read N.M.M.Roque M.E.Rostad C.Runciman S.Sachdev A.Samsonov M.Soman D.Sibeck S.Smit J.Søndergaard R.Speight S.Stavland M.Steller TianRan Sun J.Thornhill W.Thomas K.Ullaland B.Walsh D.Walton C.Wang S.Yang School of Physics and Astronomy University of LeicesterLeicesterLE17RHUK space Park Leicester University of LeicesterLeicesterLE17RHUK Mullard space Science laboratory University College LondonDorkingRH56NTUK Centre for Electronic Imaging Open UniversityMilton KeynesMK76 AAUK Birkeland Centre for space Science Department of Physics and TechnologyUniv.of BergenN-5007 BergenNorway University of Vienna A-1010 ViennaAustria space research Institute Austrian Academy of SciencesA-8042 GrazAustria National Institute of Aerospace Technology MadridSpain ESTEC European Space Agency2201 AZ NoordwijkNetherlands State Key laboratory of space Weather National Space Science CentreBeijing 100190China University of Applied Sciences and Arts Northwestern Switzerland CH-5210 WindischSwitzerland Koegl space GmbH CH-8157 DielsdorfSwitzerland space Acoustics GmbH CH-8157 DielsdorfSwitzerland Zurich University of Applied Sciences 8400 WinterhurSwitzerland Genov Solutions N-5172 LoddefjordNorway STM Engineering N-5165 LaksevagNorway John Hopkins University Applied Physics laboratory MD 20723USA NASA/Goddard space Flight Centre MD 20771USA Center for space Physics Boston UniversityBostonMA 02215USA Department of Theoretical Physics and Astrophysics Masaryk University60177 BrnoCzech Republic Institute of Physics E¨otvo¨s Lor´and University1053 BudapestHungary Aerospace Information research Institute Chinese Academy of SciencesBeijing 100045China Centro de Astrobiologia(CAB) CSIC-INTAMadridSpain

The Soft X-ray Imager(SXI)is part of the scientific payload of the Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)*** is a joint science mission between the European space Agency(ESA)and the Chinese Academy of Sciences(CAS)and is due for launch in *** is a compact X-ray telescope with a wide field-of-view(FOV)capable of encompassing large portions of Earth’s magnetosphere from the vantage point of the SMILE *** is sensitive to the soft X-rays produced by the Solar Wind Charge eXchange(SWCX)process produced when heavy ions of solar wind origin interact with neutral particles in Earth’s *** provides a mechanism for boundary detection within the magnetosphere,such as the position of Earth’s magnetopause,because the solar wind heavy ions have a very low density in regions of closed magnetic field *** sensitivity of the SXI is such that it can potentially track movements of the magnetopause on timescales of a few minutes and the orbit of SMILE will enable such movements to be tracked for segments lasting many *** is led by the University of Leicester in the United Kingdom(UK)with collaborating organisations on hardware,software and science support within the UK,Europe,China and the United States.

关键词： Soft X-ray Imaging micropore optics large area CCD

The influence of boundary conditions on the distribution of energetic electrons during collisionless magnetic reconnection

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Plasma Science and Technology 2024年第4期26卷 79-84页

作者：王磊黄灿陈冬可杨忠炜杜爱民葛亚松 CAS Engineering laboratory for Deep Resources Equipment and Technology Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029People’s Republic of China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100029People’s Republic of China State Key laboratory of space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190People’s Republic of China

We conducted 2-D particle-in-cell simulations to investigate the impact of boundary conditions on the evolution of magnetic reconnection. The results demonstrate that the boundary conditions are crucial to this evolution. Specifically, in the cases of traditional periodic boundary(PB) and fully-opened boundary(OB) conditions, the evolutions are quite similar before the system achieves the fastest reconnection rate. However, differences emerge between the two cases afterward. In the PB case, the reconnection electric field experiences a rapid decline and even becomes negative, indicating a reversal of the reconnection process. In contrast, the system maintains a fast reconnection stage in the OB case. Suprathermal electrons are generated near the separatrix and in the exhaust region of both simulation cases. In the electron density depletion layer and the dipolarization front region, a larger proportion of suprathermal electrons are produced in the OB case. Medium-energy electrons are mainly located in the vicinity of the X-line and downstream of the reconnection site in both cases. However, in the OB case, they can also be generated in the electron holes along the separatrix. Before the reverse reconnection stage, no high-energy electrons are present in the PB case. In contrast, about 20% of the electrons in the thin and elongated electron current layer are high-energy in the OB case.

关键词： magnetic reconnection electron energization particle-in-cell simulation

Acceleration of solar wind particles due to inertial Alfvén waves

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Communications in Theoretical Physics 2024年第6期76卷 137-141页

作者： Kiran Batool Imran A Khan M Shamir Abdul Kabir S Ayaz Theoretical Physics Department National Centre for PhysicsIslamabad 44000Pakistan Department of space Sciences Institute of Space TechnologyIslamabad 44000Pakistan space and Astrophysics research Lab(SARL) National Center of GIS and Space Applications(NCGSA)Islamabad 44000Pakistan Salam Chair Department of PhysicsGC University LahoreKatchery RoadLahorePunjab 54000Pakistan Department of space Science and CSPAR University of Alabama in HuntsvilleHuntsvilleAL 35899United States of America

Gaining an understanding of the effects and dynamics of the solar wind is crucial for the study of space weather,Earth's magnetosphere,spacecraft protection,the dynamics of the Solar System,and various other *** show that Alfvén waves effectively transfer energy to resonant *** study demonstrates how inertial Alfvén waves deliver their energy to resonant plasma particles in different solar environments under certain *** analysis shows that inertial Alfvén waves experience more rapid damping with increasing parallel wavenumber,ambient magnetic field strength,and particle number density,coupled with a decrease in *** rate of energy transfer to resonant particles intensifies with higher temperatures and reduced parallel wavenumber and particle number *** with higher initial velocities actively participate in Landau damping,especially in regions with a stronger ambient magnetic field.

关键词： solar wind inertial Alfven waves resonant particles

Lossless Compression Method for the Magnetic and Helioseismic Imager(MHI)Payload

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research in Astronomy and Astrophysics 2024年第4期24卷 214-221页

作者： Li-Yue Tong Jia-Ben Lin Yuan-Yong Deng Kai-Fan Ji Jun-Feng Hou Quan Wang Xiao Yang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Key laboratory of Solar Activity and space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China School of Astronomy and space Science University of Chinese Academy of SciencesBeijing 100049China Yunnan Observatories Chinese Academy of SciencesKunming 650216China

The Solar Polar-orbit Observatory(SPO),proposed by Chinese scientists,is designed to observe the solar polar regions in an unprecedented way with a spacecraft traveling in a large solar inclination angle and a small ***,one of the most significant challenges lies in ultra-long-distance data transmission,particularly for the Magnetic and Helioseismic Imager(MHI),which is the most important payload and generates the largest volume of data in *** this paper,we propose a tailored lossless data compression method based on the measurement mode and characteristics of MHI *** background out of the solar disk is removed to decrease the pixel number of an image under *** predictive coding methods are combined to eliminate the redundancy utilizing the correlation(space,spectrum,and polarization)in data set,improving the compression *** results demonstrate that our method achieves an average compression ratio of *** compression time is also less than the general observation *** method exhibits strong feasibility and can be easily adapted to MHI.

关键词： methods:data analysis techniques:image processing Sun:magnetic fields Sun:photosphere

The Astrometric Performance of the China space Station Telescope(CSST) Sky Survey in Extending the Gaia Celestial Reference Frame

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research in Astronomy and Astrophysics 2024年第8期24卷 135-142页

作者： Jun Yao Jia-Cheng Liu Niu Liu Zi Zhu Zhen-Wei Wang School of Astronomy and space Science Key Laboratory of Modern Astronomy and Astrophysics (Ministry of Education)Nanjing University University of Chinese Academy of Sciences

The multi-color imaging sky survey conducted by the China space Station Telescope (CSST) holds significant promise for advancing the development of the celestial reference *** this study,we focus on assessing the astrometric performance of the CSST celestial reference frame (CSST-CRF) in extending the Gaia Celestial Reference Frame 3 (Gaia-CRF3).First,the orientation precision of the CSST reference frame is evaluated using a simulated set of extragalactic sources with CSST g magnitudes ranging from 18 to 25 *** estimated orientation uncertainty caused by random error insignificantly affects the alignment between Gaia-CRF3 and the ***,the systematic effect of incomplete CSST sky coverage on the alignment between CSST-CRF and Gaia-CRF3 is discussed by analyzing the differences between the subset of Gaia-CRF3 in the CSST observation region (Gaia-CRF3′) and Gaia-CRF3 as a *** the third International Celestial Reference Frame (ICRF3) S/X band as an intermediate reference frame,the orientation offset between Gaia-CRF3′and GaiaCRF3 is estimated to be 20μ*** offset is marginally larger than the orientation offset between Gaia-CRF3 and the ICRF3,approximately 15μ*** residual spin and glide rate of Gaia-CRF3′are derived from the proper motions,consistent with that of Gaia-CRF3 within the formal ***,we explore the role of CSST in establishing a multi-band celestial reference frame by comparing its limiting magnitude and observation accuracy with existing catalogs in the infrared and ultraviolet *** to its broad wavelength coverage and highprecision measurements,CSST is well-positioned to make significant contributions to the development of a multiband celestial reference frame.

关键词： astrometry reference systems surveys

Service Function Chain Migration in LEO Satellite Networks

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China Communications 2024年第3期21卷 247-259页

作者： Geng Yuhui Wang Niwei Chen Xi Xu Xiaofan Zhou Changsheng Yang Junyi Xiao Zhenyu Cao Xianbin School of Electronic and Information Engineering Beihang UniversityBeijing 100191China Key laboratory of Advanced Technology of Near space Information System Ministry of Industry and Information Technology of ChinaBeijing 100191China Shanghai Key laboratory of Satellite Network Shanghai 201204China Shanghai Satellite Network research Institute Co. Ltd.Shanghai 201204China

With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)satellite *** due to the scarcity of bandwidth resources and dynamic topology of LEO satellites,the static SFC placement schemes may cause performance degradation,resource waste and even service *** this paper,we consider migration and establish an online migration model,especially considering the dynamic *** the scarcity of bandwidth resources,the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as *** to its NP-hardness,we propose a heuristic minimized dynamic SFC migration(MDSM)algorithm that only triggers the migration procedure when new SFCs are *** results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.

关键词： network function virtualization(NFV) resource allocation satellite networks service function chain(SFC) SFC migration SFC placement soft-ware defined network(SDN)

Adaptive Optimal Output Regulation of Interconnected Singularly Perturbed Systems With Application to Power Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第3期11卷 595-607页

作者： Jianguo Zhao Chunyu Yang Weinan Gao Linna Zhou Xiaomin Liu the Engineering research Center of Intelligent Control for Underground space Ministry of EducationChina University of Mining and TechnologyXuzhou 221116 the School of Information and Control Engineering China University of Mining and TechnologyXuzhou 221116 IEEE the State Key laboratory of Synthetical Automation for Process Industries Northeastern UniversityShenyang 110819China

This article studies the adaptive optimal output regulation problem for a class of interconnected singularly perturbed systems(SPSs) with unknown dynamics based on reinforcement learning(RL).Taking into account the slow and fast characteristics among system states,the interconnected SPS is decomposed into the slow time-scale dynamics and the fast timescale dynamics through singular perturbation *** the fast time-scale dynamics with interconnections,we devise a decentralized optimal control strategy by selecting appropriate weight matrices in the cost *** the slow time-scale dynamics with unknown system parameters,an off-policy RL algorithm with convergence guarantee is given to learn the optimal control strategy in terms of measurement *** combining the slow and fast controllers,we establish the composite decentralized adaptive optimal output regulator,and rigorously analyze the stability and optimality of the closed-loop *** proposed decomposition design not only bypasses the numerical stiffness but also alleviates the *** efficacy of the proposed methodology is validated by a load-frequency control application of a two-area power system.

关键词： Adaptive optimal control decentralized control output regulation reinforcement learning(RL) singularly perturbed systems(SPSs)

Ultrafast modulable 2DEG Huygens metasurface

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Photonics research 2024年第5期12卷 1004-1015页

作者： HONGXIN ZENG XUAN CONG SHIQI WANG SEN GONG LIN HUANG LAN WANG HUAJIE LIANG FENG LAN HAOYI CAO ZHENG WANG WEIPENG WANG SHIXIONG LIANG ZHIHONG FENG ZIQIANG YANG YAXIN ZHANG TIE JUN CUI Terahertz Communication laboratory School of Electronic Science and EngineeringUniversity of Electronic Science and Technology of ChinaChengdu 611730China Zhangjiang laboratory Shanghai 201210China Yangtze Delta Region Institute(Huzhou) University of Electronic Science and Technology of ChinaHuzhou 313098China National Key laboratory of Solid-State Microwave Devices and Circuits Hebei Semiconductor Research InstituteShijiazhuang 050051China Institute of Electromagnetic space and State Key laboratory of Millimeter Waves Southeast UniversityNanjing 210096China

Huygens metasurfaces have demonstrated remarkable potential in perfect transmission and precise wavefront modulation through the synergistic integration of electric resonance and magnetic ***,prevailing active or reconfigurable Huygens metasurfaces,based on all-optical systems,encounter formidable challenges associated with the intricate control of bulk dielectric using laser equipment and the presence of residual thermal effects,leading to limitations in continuous modulation ***,we present an ultrafast electrically driven terahertz Huygens metasurface that comprises an artificial microstructure layer featuring a two-dimensional electron gas(2DEG)provided by an AlGaN/GaN heterojunction,as well as a passive microstructure *** precise manipulation of the carrier concentration within the 2DEG layer,we effectively govern the current distribution on the metasurfaces,inducing variations in electromagnetic resonance modes to modulate terahertz *** modulation mechanism achieves high efficiency and contrast for terahertz wave *** investigations demonstrate continuous modulation capabilities of up to 6 GHz,a modulation efficiency of 90%,a transmission of 91%,and a remarkable relative operating bandwidth of 55.5%.These significant advancements substantially enhance the performance of terahertz metasurface ***,our work not only enables efficient amplitude modulation but also introduces an approach for the development of high-speed and efficient intelligent transmissive metasurfaces.

关键词： heterojunction precise surface