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Formation of the mass density peak at the magnetospheric equator triggered by EMIC waves

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Earth and Planetary Physics 2021年第1期5卷 32-41页

作者： ZuXiang Xue ZhiGang Yuan XiongDong Yu shiyong huang Zheng Qiao School of Electronic Information Wuhan UniversityWuhan 420072China

We report a simultaneous observation of two band electromagnetic ion cyclotron(EMIC)waves and toroidal Alfvén waves by the Van Allen Probe *** wave frequency analyses,the mass densityρis found to be locally peaked at the magnetic *** fluxes of ions(<100 eV)increase simultaneously with the appearances of EMIC waves,indicating a heating of these ions by EMIC *** addition,the measured ion distributions also support the equatorial peak formation,which accords with the result of the frequency *** formation of local mass density peaks at the equator should be due to enhancements of equatorial ion concentrations,which are triggered by EMIC waves’perpendicular heating on low energy ions.

关键词： toroidal Alfvén waves EMIC waves magnetoseismology equatorial mass density peak

Electron dynamics and wave activities associated with mirror mode structures in the near-Earth magnetotail

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Science China(Technological Sciences) 2014年第8期57卷 1541-1551页

作者： LI HuiMin ZHOU Meng DENG XiaoHua YUAN ZhiGang huang shiyong School of Electronic and Information Wuhan University Institute of Space Science and Technology Nanchang University

We report the observation of mirror mode structures by Cluster spacecraft at around X^-16 RE in the Earth’s *** wavelength of the mirror structure is larger than 7000 km,corresponding to tens of ion *** of the mirror structures are similar to those detected in the magnetosheath:the anti-correlation between the magnetic field strength and plasma density,zero phase velocity in the plasma rest frame and linear *** structures were observed in a region bounded by two dipolarizations during a substorm ***,the dipolarization process may provide a plasma condition facilitating the growth of the mirror mode *** interesting feature is the electron dynamics within the mirror *** electron energy flux has an enhancement at 0°and 180°pitch angles inside the magnetic dips of the first three mirror structures and an enhancement at 90°pitch angle inside the magnetic dip of the last *** different electron distribution inside the mirror structures might be a result of different evolution stages of the mirror *** last structure may be in the nonlinear stage of the mirror instability,whereas the three others with quasi-sinusoidal waveforms may be in the linear *** addition,we found that intense whistler waves were confined within the magnetic *** conjecture that whistler waves observed in the first three dips were generated in a remote region,then they were trapped in the mirror mode troughs and transported toward the spacecraft;while the whistler wave detected in the last dip was excited locally by the electron anisotropy instability.

关键词： mirror mode structure dipolarization electron distribution whistler wave

Observations of kinetic Alfvén waves and associated electron acceleration in the plasma sheet boundary layer

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Earth and Planetary Physics 2022年第5期6卷 465-473页

作者： ZeHao Zhang ZhiGang Yuan shiyong huang XiongDong Yu ZuXiang Xue Dan Deng Zheng huang School of Electronic Information Wuhan UniversityWuhan 430072China

Kinetic Alfvén waves(KAWs),with a strong parallel disturbed electric field,play an important role in energy transport and particle acceleration in the *** the basis of high-resolution observations of the Magnetospheric Multiscale(MMS)Mission,we present a detailed description of the acceleration process of electrons by KAWs in the plasma sheet boundary layer(PSBL).The MMS observed strong electromagnetic disturbances carrying a parallel disturbed electric field with an amplitude of up to 8 mV/*** measured ratio of the electric to magnetic field perturbations was larger than the local Alfvén speed and was enhanced as the frequency increased,consistent with the theoretical predictions for *** evidence indicates that the electromagnetic disturbances should be identified as *** the KAWs,the energy flux of electrons at energies above 1 keV in the parallel and anti-parallel directions are significantly enhanced,implying occurrences of electron beams at higher ***,the KAWs became more electrostaticlike and filled with high-frequency ion acoustic *** energy enhancement of electron beams is in accordance with the derived work done with the observed parallel disturbed electric field of KAWs,indicating electron acceleration caused by ***,these results provide direct evidence of electron acceleration by KAWs embodying electrostatic ion acoustic waves in the PSBL.

关键词： kinetic Alfvén wave plasma sheet boundary layer electron energization Poynting flux

Oxygen cyclotron harmonic waves observed using Van Allen Probes

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Science China Earth Sciences 2017年第7期60卷 1310-1316页

作者： YU XiongDong YUAN ZhiGang WANG DeDong huang shiyong LI HaiMeng YU Tao QIAO Zheng School of Electronic Information Wuhan University Institute of Space Science and Technology Nanchang University

Fine structured multiple-harmonic electromagnetic emissions at frequencies around the equatorial oxygen cyclotron harmonics are observed by Van Allen Probe A outside the core plasmasphere(L^5) off the magnetic equator(MLAT~.7.5°)during a geomagnetic storm. We find that the multiple-harmonic emissions have power spectrum density(PSD) peaks during 2–8equatorial oxygen gyroharmonics( f ~ n fO+, n=2–8), while the fundamental mode(n=1) is absent, implying that the harmonic waves are generated near the equator and propagate into the observation region. Additionally, these electromagnetic emissions are linearly polarized. Different from the equatorial noise emission that propagates considerably obliquely, these emissions have moderate wave normal angles(approximately 40°–60°), which predominately increase as the harmonic number *** their frequency and wave normal angle characteristics, it is suggested that these multiple-harmonic emissions play an important role in the dynamic variation of radiation belt electrons.

关键词： Oxygen cyclotron harmonic waves Van Allen Probes Ring current ions Radiation belt

Energetic electrons associated with magnetic reconnection in the sheath of interplanetary coronal mass ejection

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Chinese Science Bulletin 2012年第12期57卷 1455-1460页

作者： huang shiyong DENG XiaoHua ZHOU Meng YUAN ZhiGang LI HuiMin WANG DeDong School of Electronic Information Wuhan University Wuhan 430072 China State Key Laboratory of Space Weather Chinese Academy of Sciences Beijing 100190 China Institute of Space Science and Technology Nanchang University Nanchang 330031 China

Magnetic reconnection is an important universal plasma dissipation process that converts magnetic energy into plasma thermal and kinetic energy,and simultaneously changes the magnetic field *** this paper,we report the first observation of energetic electrons associated with asymmetric reconnection in the sheath of an interplanetary coronal mass *** magnetic field shear angle was about 151°,implying guide-field *** width of the exhaust was about 8×104 *** reconnection rate was estimated as 0.044-0.08,which is consistent with fast reconnection theory and previous *** observed flux enhancements of energetic electrons with energy up to 400 keV in this reconnection *** region where ener- getic electron fluxes were enhanced is located at one pair of separatrices in the higher density *** discuss these observation results,and compare with previous observations and recent kinetic simulations.

关键词：日冕物质抛射高能电子磁重联行星际动力学模拟等离子体动能转换耗散过程

Small-scale dipolarization fronts in the Earth’s magnetotail

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Earth and Planetary Physics 2019年第4期3卷 358-364页

作者： Jing huang Meng Zhou HuiMin Li XiaoHua Deng Jiang Liu shiyong huang Institute of Space Science and Technology Nanchang University Nanchang 330031 China School of Physics and Optoelectronic Engineering Xidian University Xi’an 710071 China Department of Earth Planetary and Space Sciences and Institute of Geophysics and Planetary Physics University of California Los Angeles California USA School of Electronic and Information Wuhan University Wuhan 430072 China

Previous studies suggest that dipolarization fronts (DFs) are 1 to 3RE (RE is the earth radius) wide in the dawn-dusk direction. Recent kinetic simulations have found that DFs may break up into small-scale structures after they are produced by reconnection. Motivated by this simulation, we revisited the scale size of DFs in the dawn-dusk direction by using Cluster observations during the years when the inter-distance among Cluster spacecraft was between 1000 and 2000 km. We selected the DFs that were detected by more than one spacecraft and estimated the radii of these DFs by a simple geometrical analysis, which is based on comparison of DF normals observed by different spacecraft. We found a few DFs that were only a few ion inertial lengths in the dawn-dusk direction. These results point out the importance of multi-scale coupling during the evolution of DFs.

关键词： dipolarization front small scale Earth's magnetotail

TMAS:A transaction misbehavior analysis scheme for blockchain

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Blockchain(Research and Applications) 2024年第3期5卷 42-52页

作者： shiyong huang Xiaohan Hao Yani Sun Chenhuang Wu Huimin Li Wei Ren Kim-Kwang Raymond Choo School of Computer Science China University of GeosciencesWuhan430074China Artificial Intelligence Thrust Information HubHong Kong University of Science and TechnologyGuangzhou511400China Yunnan Key Laboratory of Blockchain Application Technology Yunnan Innovation Institute of Beihang UniversityKunming650233China Fujian Key Laboratory of Financial Information Processing Putian UniversityPutian351100China Department of Information Systems and Cyber Security University of Texas at San AntonioSan AntonioTX 78249-0631USA

Blockchain-based cryptocurrencies,such as Bitcoins,are increasingly ***,the decentralized and anonymous nature of these currencies can also be(ab)used for nefarious activities such as money laundering,thus reinforcing the importance of designing tools to effectively detect malicious transaction *** this paper,we propose TMAS,a transaction misbehavior analysis scheme for blockchain-based ***,the proposed system includes ten features in the transaction graph,two heuristic money laundering models,and an analysis method for account linkage,which identifies accounts that are distinct but controlled by an identical *** evaluate the effectiveness of our proposed indicators and models,we analyze 100 million transactions and compute transaction features,and are able to identify a number of suspicious ***,the proposed methods can be applied to other cryptocurrencies,such as token-based cryptocurrencies(e.g.,Bitcoins)and account-based cryptocurrencies(e.g.,Ethereum).

关键词： Blockchain Anti-money laundering Bitcoin Cyptocurrency

Excitation of extremely low-frequency chorus emissions: The role of background plasma density

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Earth and Planetary Physics 2019年第1期3卷 1-7页

作者： XiongDong Yu ZhiGang Yuan shiyong huang Fei Yao Zheng Qiao John R.Wygant Herbert O.Funsten School of Electronic Information Wuhan University School of Physics and Astronomy University of Minnesota Los Alamos National Laboratory

Low-frequency chorus emissions have recently attracted much attention due to the suggestion that they may play important roles in the dynamics of the Van Allen ***, the mechanism(s) generating these low-frequency chorus emissions have not been well understood..In this letter, we report an interesting case in which background plasma density lowered the lower cutoff frequency of chorus emissions from above 0.1 f_(ce)(typical ordinary chorus) to 0.02 f_(ce)(extremely low-frequency chorus).Those extremely low-frequency chorus waves were observed in a rather dense plasma, where the number density N_e was found to be several times larger than has been associated with observations of ordinary chorus *** suprathermal electrons whose free energy is supplied by anisotropic temperatures, linear growth rates(calculated using in-situ plasma parameters measured by the Van Allen Probes) show that whistler mode instability can occur at frequencies below 0.1 f_(ce) when the background plasma density N_e *** when N_e reaches 90 cm–3 or more, the lowest unstable frequency can extend to 0.02 f_(ce) or even less, which is consistent with satellite ***, our results demonstrate that a dense background plasma could play an essential role in the excitation of extremely lowfrequency chorus waves by controlling the wave growth rates.

关键词： low-frequency chorus emissions anisotropic temperature instability whistler mode Van Allen Probes linear growth rate

Observation of directional change of core field inside flux ropes within one reconnection diffusion region in the Earth's magnetotail

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Chinese Science Bulletin 2014年第34期59卷 4797-4803页

作者： shiyong huang Ye Pang Zhigang Yuan Xiaohua Deng Jiansen He Meng Zhou Huishan Fu Song Fu Huimin Li Dedong Wang Haimeng Li School of Electronic and Information Wuhan University Institute of Space Science and Technology Nanchang University School of Earth and Space Sciences Peking University Space Science Institute School of Astronautics Beihang University

Two consecutive magnetic flux ropes, separated by less than 30 s(Dt \ 30 s), are observed within one magnetic reconnection diffusion region without strong guide field in the Earth's magnetotail by Cluster multispacecraft. The flux ropes are characterized by bipolar signatures of the south–north magnetic field component Bz accompanied with strong core magnetic field By, intense current J and density depletions inside of them. In spite of the small but non-trivial global scale negative guide field(–By), there exists a directional change of the core fields of two flux ropes, i.e.,-Byfor the first one, and Byfor the second one. The directions of the core fields are the same as the ambient cross-tail magnetic field component(By) just outside of flux ropes. Therefore, we suggest that the core field of flux ropes is formed by compression of the local preexisting Byand that the directional change of core field is due to the change of local preexisting By. Such a change in ambient Bymight be caused by some microscale physics.

关键词：磁通量绳索字段扩散地球观测连接磁场分量