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The response of plasma parameters and energy transport in the plasma sheet to interplanetary magnetic field B_z

Science China(Technological Sciences) 2021年第7期64卷 1528-1534页

作者： REN GanMing CAO JinBin YANG Jian dunlop malcolm wray School of Space and Environment Beihang UniversityBeijing100191China Key Laboratory of Space Environment Monitoring and Information Processing of MIIT Beijing102206China

We use 9 years data of Cluster to study the dependencies of plasma parameters and energy transport in the plasma sheet on the lasting time of northward/southward interplanetary magnetic field(IMF). The plasma parameters and energy transport in the plasma sheet always respond to the change of IMF direction by more or less time. The ion density starts to increase/decrease remarkably at 80 min after northward/southward IMF turning. The ion temperature starts to decrease at 25 min after northward IMF turning, whereas it starts to increase at 80 min after southward IMF turning. The earthward convection velocity within15 min after northward IMF turning almost equals to that within 15 min period after southward IMF turning. However at time greater than 15 min after southward IMF turning, the earthward convection velocity under southward IMF starts to remarkably increase. The response time(15 min) of magnetospheric convection velocity is well consistent with the response times of nightside ionospheric convection to southward IMF turning. The enthalpy flux is larger than kinetic flux by about three orders of magnitudes, and thus the enthalpy flux plays a dominant role in the plasma sheet energy transport. The enthalpy flux does not weaken immediately after northward IMF turning. The enthalpy flux within 15 min after northward IMF turning is comparable to or even slightly larger than that within 15 min after southward IMF. The enthalpy flux starts to decrease at times greater than15 min after northward IMF turning, whereas it starts to increase at times greater than 15 min after southward IMF turning. The result that the enhanced energy transport during the 15 min period after northward IMF turning may explain previous observation that substorms frequently occur shortly after northward IMF turning.

关键词： plasma sheet energy transport enthalpy flux response time

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Multi-spacecraft observations of earthward flow bursts

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Science China(Technological Sciences) 2012年第5期55卷 1305-1311页

作者： MA YuDuan CAO JinBin REME Henry DANDOURAS Iannis dunlop malcolm LUCEK Elisabeth School of Astronautics Beihang UniversityBeijing 100191China SOA Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China Centre d'Etude Spatiale des Rayonnements Toulouse 31028France RutherforAppleton Laboratory OxfordshireUK Blackett Laboratory Imperial College LondonLondon SW72AZUK

On the basis of the plasma, electric and magnetic fields jointly observed by Cluster and the Double Star TC-I spacecraft in the Earth＇s magnetotail, we have investigated the earthward flow bursts by introducing the momentum equation in the X-direction in the ideal conditions of magneto hydrodynamics （MHD）. One earthward flow burst with a peak in excess of 500 km/s was selected, when the four spacecraft of Cluster were located around -16 RE and TC-1 was located around -10 RE in the X-direction. The inter-spacecraft distances in Y and Z directions were smaller than the statistical spatial scales of the bursty bulk flows. When the Y components of E and -VxB were compared, there was no clear breakdown of the frozen-in condition during the earthward flow burst. With the measured plasma and magnetic parameters from two spacecraft at different positions in the magnetotail, the X component of the pressure gradient was calculated. Magnetic tension was calculated using the mag- netic field measured at four points, which could be compared with the assumed constant in the past research with single satel- lite. When the pressure gradient and the magnetic tension were put into the MHD momentum equation, some samples of the earthward flow bursts were accelerated and some were decelerated. The braking process of the earthward flow burst was more complicated than what the past results had shown. The accelerated samples accounted for about one third of the whole earth- ward flow bursts and discontinuously located among the decelerated elements. The original single earthward flow burst event might be split into several short flow bursts when it was moving to the Earth. Our results may partly illustrate that the duration of fast flows during three phases of substorm becomes short near the Earth. The results are consistent with the past results that fast flows intrude to places earthward the typical braking region.

关键词： flow burst pressure gradient magnetic tension braking

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Surgical intervention combined with weight-bearing walking training promotes recovery in patients with chronic spinal cord injury:a randomized controlled study

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Neural Regeneration Research 2024年第12期19卷 2773-2784页

作者： Hui Zhu James D.Guest Sarah dunlop Jia-Xin Xie Sujuan Gao Zhuojing Luo Joe E.Springer Wutian Wu Wise Young Wai Sang Poon Song Liu Hongkun Gao Tao Yu Dianchun Wang Libing Zhou Shengping Wu Lei Zhong Fang Niu Xiaomei Wang Yansheng Liu Kwok-Fai So Xiao-Ming Xu Kunming Tongren Hospital KunmingYunnan ProvinceChina Neurological Surgery and the Miami Project to Cure ParalysisMiller School of MedicineUniversity of MiamiMiamiFLUSA School of Biological Sciences The University of Western AustraliaPerthWAAustralia Minderoo Foundation PerthWAAustralia Clinical Center for Spinal Cord Injury Kunming General Hospital of Chengdu Military CommandKunmingYunnan ProvinceChina Department of Biostatistics and Health Data Science Indiana University School of MedicineIndianapolisINUSA Department of Orthopedic Spinal Surgery Xijing HospitalFourth Military Medical UniversityXi’anShaanxi ProvinceChina Spinal Cord and Brain Injury Research Center Department of Physical Medicine and RehabilitationUniversity of Kentucky College of MedicineLexingtonKYUSA Guangdong-HongKong-Macao Institute of CNS Regeneration Jinan UniversityGuangzhouGuangdong ProvinceChina W.M.Keck Center for Collaborative Neuroscience Rutgers UniversityPiscatawayNJUSA Neurosurgery Department Chinese University of Hong KongPrince of Wales HospitalHong Kong Special Administration RegionChina Spinal Cord and Brain Injury Research Group Stark Neurosciences Research InstituteDepartment of Neurological SurgeryIndiana University School of MedicineIndianapolisINUSA

For patients with chronic spinal cord injury,the co nventional treatment is rehabilitation and treatment of spinal cord injury complications such as urinary tract infection,pressure sores,osteoporosis,and deep vein *** is rarely perfo rmed on spinal co rd injury in the chronic phase,and few treatments have been proven effective in chronic spinal cord injury *** of effective therapies fo r chronic spinal co rd injury patients is *** conducted a randomized controlled clinical trial in patients with chronic complete thoracic spinal co rd injury to compare intensive rehabilitation(weight-bearing walking training)alone with surgical intervention plus intensive *** clinical trial was registered at ***(NCT02663310).The goal of surgical intervention was spinal cord detethering,restoration of cerebrospinal fluid flow,and elimination of residual spinal cord *** found that surgical intervention plus weight-bearing walking training was associated with a higher incidence of American Spinal Injury Association Impairment Scale improvement,reduced spasticity,and more rapid bowel and bladder functional recovery than weight-bearing walking training ***,the surgical procedures and intensive rehabilitation were *** Spinal Injury Association Impairment Scale improvement was more common in T7-T11 injuries than in T2-T6 *** combined with rehabilitation appears to have a role in treatment of chronic spinal cord injury patients.

关键词： chronic spinal cord injury intensive rehabilitation locomotor training neurological recovery surgical intervention weightbearing walking training

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Relationship between FAC at plasma sheet boundary layers and AE index during storms from August to October,2001

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Science China(Technological Sciences) 2008年第7期51卷 842-848页

作者： dunlop M Imperial College London London SW7 2AZ UK

Unlike the previous single (dual) satellite observation, the four Clusterll satellites make it possible to directly compute the continuous field-aligned current (FAC) density according to the magnetic data from them and to enable the investigation of the relationship between the FAC and geomagnetic activity. This paper analyzes the observation data when the Cluster satellites crossed the plasma sheet boundary layer (PSBL) in the magnetotail during the two magnetic storms in August to October 2001. According to the data, during the magnetic storms the relationship between the variations of FAC and AE index turned out to be: 1) FAC was obviously increasing during the storms; 2) FAC density was approximately negatively correlated with AE index from the sudden commencement to the early main phase of the storm; 3) they were approximately positively correlated during the late main phase and early recovery phase; 4) they were no apparent correlation during the late recovery phase.

关键词： ionosphere-magnetosphere storm cases FAC AE index

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Observations of the step-like accelerating processes of cold ions in the reconnection layer at the dayside magnetopause

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Science Bulletin 2018年第1期63卷 31-37页

作者： Qinghe Zhang Michael Lockwood John C.Foster Qiugang Zong malcolm W.dunlop Shunrong Zhang Joran Moen Beichen Zhang Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China Department of Meteorology University of ReadingReading RG6 6BBUK MIT Haystack Observatory WestfordMA 01886USA School of Earth and Space Sciences Peking UniversityBeijing 100087China Space Sciences Division SSTDRutherford Appleton LaboratoryDidcot OX11 OQXUK Department of Physics University of OsloBlindern 0316OsloNorway SOA Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China

Cold ions of plasmaspheric origin have been observed to abundantly appear in the magnetospheric side of the Earth's magnetopause. These cold ions could affect the magnetic reconnection processes at the magnetopause by changing the Alfvén velocity and the reconnection rate, while they could also be heated in the reconnection layer during the ongoing reconnections. We report in situ observations from a partially crossing of a reconnection layer near the subsolar magnetopause. During this crossing, step-like accelerating processes of the cold ions were clearly observed, suggesting that the inflow cold ions may be separately accelerated by the rotation discontinuity and slow shock inside the reconnection layer.

关键词： Cold ions Magnetic reconnection Ion accelerations Magnetopause

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SuperDARN CUTLASS Finland radar observations of high-latitude magnetic reconnections under northward interplanetary magnetic field (IMF) conditions

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Science China(Technological Sciences) 2012年第5期55卷 1207-1216页

作者： ZHANG QingHe LIU RuiYuan YANG HuiGen HU HongQiao ZHANG BeiChen dunlop malcolm LESTER Mark BOGDANOVA Yulia WALSH Andrew SOA Key Laboratoryfor Polar Science Polar Research Institute of ChinaShanghai 200136China Space Science Department Rutherford-Appleton LaboratoryChiltonDidcotUK Department of Physics and Astronomy University of LeicesterLeicesterUK Mullard Space Science Laboratory University College LondonDorkingSurreyUK

A number of backscatter power enhancement events with ＂equatorward-moving radar auroral forms＂ in the high-latitude ionosphere were observed by SuperDARN CUTLASS Finland radar when the IMF was northward during 09：00 -10：00 UT on 26 March 2004. These events were also associated with sunward flow enhancements at each location in the Northern Hemisphere which were shown in ionospheric convections measured by the SuperDARN radars. These are typical features of high-latitude （lobe） magnetic reconnections. The durations of the velocity enhancements imply that the evolution time of the lobe reconnec- tions is about 8-16 rain from their origin at the reconnection site to their addition to the magnetotall lobe again. In additional, the Double Star TC-1 spacecraft was moving from magnetosheath into magnetosphere, and crossing the magnetopause near the subsolar region during this interval, and observed typical low-latitude magnetic reconnection signatures. This infers that the dayside high- and low-latitude reconnections may occur simultaneously.

关键词： high-latitude magnetic reconnection equatorward-moving radar auroral form evolution time of the lobe reconnections

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Coordinated Cluster/Double Star observations of dayside flux transfer events on 6 April 2004

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Science China(Technological Sciences) 2008年第10期51卷 1611-1619页

作者： Malcom W. dunlop Space Science and Technology Department Rutherford Appleton Laboratory Chilton Oxfordshire OX 11 0QX UK

With the Double Star Program TC1 in the equatorial orbit and Cluster tetrahedron in the high latitude polar orbit, a conjunct observation of FTEs on the dayside magnetopause (MP) on April 6, 2004 is presented in this study. The FTEs observed by TC1 at low latitudes are characterized to be generated in the subsolar region and the obtained flux tube axes orientate along the predicted low latitude component magnetic reconnection X-line, indicating that these FTEs were more likely to be generated through multiple X-line reconnection or single X-line bursty reconnec-tion. During the same period, Cluster also encountered a series of magnetosheath FTEs with their axes pointing roughly along the interplanetary magnetic field. At last, the global FTE configuration is obtained from observations in different loca-tions, which is in good agreement with the "elbow shape" model.

关键词： magnetopause magnetic reconnection FTEs generation mechanism global configuration

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磁尾的等离子体片边界层场向电流密度与地磁活动指数Kp的关系分析

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中国科学：技术科学 2011年第11期41卷 1499-1504页

作者：程征伟史建魁 ZHANG Tie Long dunlop malcolm 刘振兴中国科学院空间科学与应用研究中心空间天气学国家重点实验室北京100190 Space Research Institute Austrian Academy of Sciences Graz A-8010 Austria SSTD Rutherford Appleton Laboratory SW7 2AZ UK

对2001年7月～10月Cluster穿越磁尾等离子体片边界层期间观测到的172个场向电流事件进行了研究,主要分析了等离子体片边界层场向电流特性与地磁活动指数之间的关系.研究结果表明:1)等离子体片边界层场向电流的相对发生率随地磁活动的增... 详细信息

对2001年7月～10月Cluster穿越磁尾等离子体片边界层期间观测到的172个场向电流事件进行了研究,主要分析了等离子体片边界层场向电流特性与地磁活动指数之间的关系.研究结果表明:1)等离子体片边界层场向电流的相对发生率随地磁活动的增强而增加;2)等离子体片边界层场向电流密度随Kp指数的增大而增大;在磁暴的主相阶段,场向电流迅速增大,电流密度最大达到19.05nA/m2,同时Kp增大至5;3)地磁活动指数Kp与等离子体片边界层区场向电流密度有着一致的变化关系.然而,当AE800nT时,场向电流密度随着AE的增加而减小.从而说明,等离子体片边界层场向电流密度与Kp指数的变化关系更为密切.

关键词：场向电流等离子体片边界层 Kp指数 AE指数

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A new processing method for the AE index

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Science China(Technological Sciences) 2008年第10期51卷 1713-1720页

作者： W. BAUMJOHANN M. dunlop Space Research Institute Austrian Academy of Sciences Graz Austria Space Sciences Division Rutherford Appleton Laboratory Chilton Didcot United Kingdom

In this paper, we introduce an effective processing method to acquire the time de-rivative of the AE index as a coefficient. Using this coefficient, the AE index can be divided into the four stages: quiet, ascending, descending and active stages. The statistical results show that the ascending and descending stages of the AE index are dominant and occupy two thirds of the whole period. An analysis of the rela-tionship between the occurrence frequencies of the Dst index and AE index in solar cycle 23 shows that the monthly variation of the occurrence frequencies of the ascending stage of AE is closely related to the decrease of the Dst index.

关键词： AE index Dst index FIR filter substorm

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Heading control strategy assessment for coaxial compound helicopters

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Chinese Journal of Aeronautics 2019年第9期32卷 2037-2046页

作者： Ye YUAN Douglas THOMSON Renliang CHEN Richard dunlop National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics&AstronauticsNanjing 210016China University of Glasgow Glasgow G12 8QQUnited Kingdom

The coaxial compound helicopter has two possible strategies for heading control: collective differential and rudder deflection. A flight dynamics model is developed to assess the effect of different heading control strategies. This includes the trim characteristics, steady flight performance,controllability, and manoeuvrability. The trim study demonstrates that heading control strategies are less influential on trim results, and the steady flight performance is also not significantly affected by the heading control strategy adopted. The controllability analysis shows although heading bandwidth and phase delay results at various speeds with different heading control strategies are all satisfied, the control derivative of the collective differential decreases as speed increases, and its heading aggressive agility is degraded into Level 3 in high-speed flight. In addition, using collective differential would lead to severe heading-rolling coupling as forward speed increases. On the contrary, the control derivative and aggressive agility of the rudder deflection is improved with forward speed, and there is no evidence of heading-rolling coupling. Finally, the transient turn MissionTask-Element(MTE) is utilized to investigate the heading manoeuvre characteristics in different heading control strategies, which indicates that the collective differential would add the amplitude of control input and the power consumption during this MTE.

关键词： Coaxial compound helicopter Control strategy Handling qualities Helicopter flight dynamics Helicopter performance

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