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On the ion distributions at the separatrices during symmetric magnetic reconnection

Earth and Planetary Physics 2021年第2期5卷 205-217页

作者： HongTao Huang yiqun yu JinBin Cao Lei Dai RongSheng Wang School of Space and Environment Beihang UniversityBeijing 100191China Key Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing 100191China State Key Laboratory of Space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Key Laboratory of Geospace Environment Department of Geophysics and Planetary ScienceUniversity of Science and Technology of ChinaHefei 230026China

A particle-in-cell simulation of symmetric reconnection with zero guide field is carried out to understand the dynamics of ions along the *** the investigation of ion velocity distributions at different moments and locations along the separatrices,a typical distribution is found:two counter-streaming populations in the perpendicular direction,with another two populations accelerated into distinct energy levels in the parallel *** tracing of ions reveals that the counter-streaming cores are mostly composed of ions initially located at the same side of the separatrix,while the other two accelerated populations in the parallel direction are composed of ions crossing through the neutral *** analysis of energy conversion of these populations,it is found that the ion energization along the separatrix is attributable primarily to the Hall electric field,while that in the region between the two separatrices is caused primarily by the induced reconnection electric *** the counter-streaming population,the low-energy ions that cross the separatrix twice are affected by both Hall and reconnection electric fields,while the high-energy ions that directly enter the separatrix from the unperturbed plasma are energized mainly by the Hall electric *** the two energized populations in the parallel direction,the ions with lower-energy are accelerated mainly by the in-plane electric field and the Hall electric field on the opposite side of the separatrix,whereas the ions with higher-energy not only experience the same energization process but also are constantly accelerated by the reconnection electric field.

关键词： magnetic reconnection particle-in-cell simulation energetic particles

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A storm-time ring current model(STRIM)

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Science China Technological Sciences 2024年第12期67卷 3890-3908页

作者： yu yiqun MA LongXing WEI ZiMing AN DePeng WU HaiJun LU Haoyu CAO JinBin School of Space and Earth Sciences Beihang University Key Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information Technology

The ring current, one of the most important current systems around the Earth, intensifies during geomagnetic storms and is believed to be the main reason for large-scale magnetic field perturbations in the geospace environment. Understanding how the ring current builds up and evolves during geomagnetic storms is of great importance not only for advancing the knowledge of the Sun-Earth system but also for improving the modeling capability of predicting hazardous space weather events. Focusing on the national strategic needs in the space weather prediction, in this study, we establish a ring current model named storm time ring current model(STRIM). The STRIM comprehensively embraces key physical processes in association with ring current dynamics,including plasma source injections from the nightside plasmasheet and transport around the Earth, charge-exchange with neutral hydrogens, Coulomb collisions with thermal plasma, wave-particle interactions, field line curvature scattering, and precipitation loss down to the upper atmosphere. The electric fields needed for particle motion can be optionally taken from empirical models or self-consistently calculated, while the magnetic field configuration is obtained from Tsyganenko 2005 model. Simulation results are verified against the published literature and validated with in-situ satellite or ground-based observations and are found to have the same high-level capability and fidelity as other well-known published models. We also discuss future tasks of fostering the model's performance and potential applications.

关键词： kinetic ring current models bounce-averaged Fokker-Planck equation Earth inner magnetosphere ring current dynamics magnetic storms

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Effects of a dipole-like crustal field on solar wind interaction with Mars

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Earth and Planetary Physics 2020年第1期4卷 23-31页

作者： ShiBang Li Haoyu Lu Jun Cui yiqun yu Christian Mazelle yun Li JinBin Cao School of Space and Environment Beihang UniversityBeijing 100191China Key Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing 100191China School of Atmospheric Sciences Sun Yat-Sen UniversityZhuhai Guangdong 519082China CNRS Institute de Recherche en Astrophysique et PlanétologieToulouseFrance

A three-dimensional four species multi-fluid magnetohydrodynamic (MHD) model was constructed to simulate the solar wind global interaction with Mars. The model was augmented to consider production and loss of the significant ion species in the Martian ionosphere, i.e., H^+, O2^+, O^+, CO^+2, associated with chemical reactions among all species. An ideal dipole-like local crustal field model was used to simplify the empirically measured Martian crustal field. Results of this simulation suggest that the magnetic pile-up region (MPR) and the velocity profile in the meridian plane are asymmetric, which is due to the nature of the multi-fluid model to decouple individual ion velocity resulting in occurrence of plume flow in the northern Martian magnetotail. In the presence of dipole magnetic field model, boundary layers, such as bow shock (BS) and magnetic pile-up boundary (MPB), become protuberant. Moreover, the crustal field has an inhibiting effect on the flux of ions escaping from Mars, an effect that occurs primarily in the region between the terminator (SZA 90°) and the Sun Mars line of the magnetotail (SZA 180°), partially around the terminator region. In contrast, near the tailward central line the crustal field has no significant impact on the escaping flux.

关键词： solar wind interaction with Mars global MHD simulation crustal field escape flux

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Effects of polarization-reversed electromagnetic ion cyclotron waves on the ring current dynamics

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Earth and Planetary Physics 2022年第4期6卷 329-338页

作者： MingHui Zhu yiqun yu Xing Cao BinBin Ni XingBin Tian JinBin Cao Vania K.Jordanova School of Space and Environment Beihang UniversityBeijing 100191China Key Laboratory of Space Environment Monitoring and Information Processing Ministry of Industry and Information TechnologyBeijing 100191China Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China Chinese Academy of Sciences Center for Excellence in Comparative Planetology Hefei 230026China Space Science and Application Los Alamos National LaboratoryLos Alamos87545New MexicoUSA

Electromagnetic ion cyclotron(EMIC)waves are widely believed to play an important role in influencing the radiation belt and ring current *** studies have investigated the effects or characteristics of EMIC waves by assuming their left-handed ***,recent studies have found that the reversal of polarization,which occurs at higher latitudes along the wave propagation path,can change the wave-induced pitch angle diffusion *** such a polarization reversal can influence the global ring current dynamics remains *** this study,we investigate the ring current dynamics and proton precipitation loss in association with polarization-reversed EMIC waves by using the ring current-atmosphere interactions model(RAM).The results indicate that the polarization reversal of H-band EMIC waves can truly decrease the scattering rates of protons of 10 to 50 keV or>100 keV in comparison with the scenario in which the EMIC waves are considered purely left-handed ***,the global ring current intensity and proton precipitation may be slightly affected by the polarization reversal,especially during prestorm time and the recovery phase,but the effects are not large during the main *** is probably because the H-band EMIC waves contribute to the proton scattering loss primarily at E<10 keV,an energy range that is not strongly affected by the polarization reversal.

关键词： electromagnetic ion cyclotron waves polarization reversal ring current

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Simulating the Global Distribution of particle precipitation in response to ULF waves

Simulating the Global Distribution of particle precipitation...

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2022年中国地球科学联合学术年会

作者： Longxing Ma yiqun yu Beihang University

The global distribution of particle precipitation is closely related to the formation and evolution of aurora. ULF waves in the magnetosphere are believed to contribute to many auroral activities, such as the auroral arcs, and the fluctuations of auroral intensity. In this study, we simulate the global distribution of both ion and electron precipitations using a ring current model which takes into account ULF waves and investigates their relative roles in supplying energy sources to the ionosphere.

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偶极化锋面上能量转化与分配的模拟研究

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地球物理学报 2022年第7期65卷 2412-2420页

作者：黄宏韬於益群北京航空航天大学空间与环境学院北京100191

偶极化锋面在地球磁尾的能量和物质传输中有着重要的作用.以往的研究表明,偶极化锋面是磁尾磁重联释放能量发生能量转化的主要场所.然而,在这些被释放的磁能中,离子和电子各自所获得的能量总量缺少定量的研究.本文利用全粒子数值模拟来... 详细信息

偶极化锋面在地球磁尾的能量和物质传输中有着重要的作用.以往的研究表明,偶极化锋面是磁尾磁重联释放能量发生能量转化的主要场所.然而,在这些被释放的磁能中,离子和电子各自所获得的能量总量缺少定量的研究.本文利用全粒子数值模拟来研究磁重联中偶极化锋面上的能量转化与能量分配.结果表明,离子获得了总能量的90%,电子只获得了总能量的10%.其获得能量主要来自于Y方向分量的贡献.另外,本文还研究了引导场对能量转化与分配的影响.研究表明当引导场大小为0.5倍初始磁场时,离子获得了多达95%的能量,电子只获得了5%的能量.同时,引导场导致磁重联拓扑结构的改变,使得能量转化项Z方向分量的贡献不再是可忽略的.这些研究结果有助于我们进一步理解偶极化锋面在磁尾粒子加速与能量转化过程中的作用.

关键词：偶极化锋面全粒子模拟能量转化能量分配

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Ionospheric modulation by EMIC wave driven proton precipitation: observations and simulations

Ionospheric modulation by EMIC wave driven proton precipitat...

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2022年中国地球科学联合学术年会

作者： Xingbin Tian yiqun yu Longxing Ma Beihang University

Protons of tens of keV can be resonantly scattered by electromagnetic ion cyclotron (EMIC) waves excited in the magnetosphere, resulting in further proton precipitation down to the upper atmosphere. In this study, we report for the first time the ionospheric height-dependent ionization in response to EMIC-associated isolated proton aurora (IPA) using simultaneous space-borne and ground-based measurements.

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亚极光区极化流发生期间电离层离子下行的统计

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空间科学学报 2022年第1期42卷 73-81页

作者：魏冬於益群北京航空航天大学空间与环境学院北京102206 工业和信息化部空间环境监测与信息处理重点实验室北京102206

亚极光区极化流是地球磁层–电离层耦合过程中最重要的现象之一,对电离层具有重要的调制作用。多数情况下,亚极光区极化流发生时会伴随局地离子上行流动,目前已对其有充分的研究,但对离子下行的研究却甚少。本文分析了DMSP卫星在2001-2 ... 详细信息

亚极光区极化流是地球磁层–电离层耦合过程中最重要的现象之一,对电离层具有重要的调制作用。多数情况下,亚极光区极化流发生时会伴随局地离子上行流动,目前已对其有充分的研究,但对离子下行的研究却甚少。本文分析了DMSP卫星在2001-2 015年间16个地磁暴中的观测数据,在483个亚极光区极化流事件中找到102个离子下行事件,并对其开展统计研究,分析离子下行在亚极光区极化流事件中的发生率,在南北半球的分布以及有助于离子下行形成的条件。结果表明:离子下行在亚极光区极化流事件中发生概率较小,离子下行事件的发生与分布具有比较明显的南北半球差异,并且亚极光区极化流的速度与离子下行速度具有高度相关性,表现为线性关系;而离子下行极有可能是因为双极扩散与地球重力共同作用而产生的,并且离子的热运动强弱对离子下行的速度大小也具有重要影响。这些研究结果有助于进一步理解亚极光区极化流对地球电离层动力学的调制作用。

关键词：亚极光区极化流离子下行分布特征统计研究

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Neural substrates for regulating self-grooming behavior in rodents

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2024年第10期25卷 841-856页

作者： Guanqing LI Chanyi LU Miaomiao YIN Peng WANG Pengbo ZHANG Jialiang WU Wenqiang WANG Ding WANG Mengyue WANG Jiahan LIU Xinghan LIN Jian-Xu ZHANG Zhenshan WANG yiqun yu yun-Feng ZHANG State Key Laboratory of Integrated Management of Pest Insects and Rodents Institute of ZoologyChinese Academy of SciencesBeijing 100101China CAS Center for Excellence in Biotic Interactions University of Chinese Academy of SciencesBeijing 100101China School of Life Sciences Hebei UniversityBaoding 071002China State Key Laboratory of Molecular Development Biology Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing 100101China Department of Rehabilitation Medicine Tianjin Huanhu HospitalTianjin 300350China Medical Center for Human Reproduction Beijing Chao-Yang HospitalCapital Medical UniversityBeijing 100101China Department of Gastrointestinal Surgery the People’s Hospital of Zhaoyuan CityZhaoyuan 265400China School of Life Sciences Division of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefei 230026China Department of Otolaryngology EyeEarNose&Throat HospitalFudan UniversityShanghai 200031China Ear Nose&Throat InstituteEyeEarNose&Throat HospitalFudan UniversityShanghai 200031China Clinical and Research Center for Olfactory Disorders EyeEarNose&Throat HospitalFudan UniversityShanghai 200031China

Grooming,as an evolutionarily conserved repetitive behavior,is common in various animals,including humans,and serves essential functions including,but not limited to,hygiene maintenance,thermoregulation,de-arousal,stress reduction,and social *** rodents,grooming involves a patterned and sequenced structure,known as the syntactic chain with four phases that comprise repeated stereotyped movements happening in a cephalocaudal progression style,beginning from the nose to the face,to the head,and finally ending with body *** context-dependent occurrence of grooming behavior indicates its adaptive *** review briefly summarizes the neural substrates responsible for rodent grooming behavior and explores its relevance in rodent models of neuropsychiatric disorders and neurodegenerative diseases with aberrant grooming *** further emphasize the utility of rodent grooming as a reliable measure of repetitive behavior in neuropsychiatric models,holding promise for translational ***,we mainly focus on rodent ***(grooming being applied on one animal by its conspecifics via licking or carefully nibbling)and heterogrooming(a form of grooming behavior directing towards another animal,which occurs in other contexts,such as maternal,sexual,aggressive,or social behaviors)are not covered due to space constraints.

关键词： Grooming Repetitive behavior Syntactic chain Cephalocaudal progression Neuropsychiatric disorders

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工业企业污染物排放总量控制的有效措施

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上海环境科学 2000年第9期19卷 452-453页

作者：余一群上海市徐汇区环境监测站上海200032

生活和居住的环境质量越来越受人们重视,这对作为主要污染源的工业企业的环保治理提出了更高要求。根据工业企业在推行污染物排放总量控制制度过程中的实际认识,提出了“防治结合,以管促治”的工作方针,介绍了结合技术改造,落实环保措施... 详细信息

生活和居住的环境质量越来越受人们重视,这对作为主要污染源的工业企业的环保治理提出了更高要求。根据工业企业在推行污染物排放总量控制制度过程中的实际认识,提出了“防治结合,以管促治”的工作方针,介绍了结合技术改造,落实环保措施,加强现场管理等几方面的有效措施。

关键词：工业污染物污染物排放总量控制措施工业企业

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