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A study on the dynamic spectral indices for SEP events on 2000 July 14 and 2005 January 20

Research in Astronomy and Astrophysics 2020年第3期20卷 129-135页

作者： ming-xian zhao Gui-ming Le Key Laboratory of Space Weather National Center for Space WeatherChina Meteorological Administration.Beijing 100081China

We have studied the dynamic proton spectra for the two solar energetic particle(SEP)events on2000 July 14(hereafter GLE59)and 2005 January 20(hereafter GLE69).The source locations of GLE59 and GLE69 are N22 W07 and N12 W58 *** fluxes>30 Me V have been used to compute the dynamic spectral indices of the two SEP *** results show that spectral indices of the two SEP events increased more swiftly at early times,suggesting that the proton fluxes>30 Me V might be accelerated particularly by the concurrent flares at early times for the two SEP *** the GLE69 with source location at N12 W58,both flare site and shock nose are well connected with the Earth at the earliest ***,only the particles accelerated by the shock driven by eastern flank of the CME can propagate along the interplanetary magnetic field line to the Earth after the *** the GLE59 with source location at N22 W07,only the particles accelerated by the shock driven by western flank of the associated CME can reach the Earth after the *** results also show that there was slightly more than one hour during which the proton spectra for GLE69 are softer than that for GLE59 after the flares,suggesting that the shock driven by eastern flank of the CME associated with GLE69 is weaker than the shock driven by the western flank of the CME associated with *** results support that quasi-perpendicular shock has stronger potential in accelerating particles than the quasi-parallel *** results also suggest that only a small part of the shock driven by western flank of the CME associated with the GLE59 is quasi-perpendicular.

关键词： Sun:flares-Sun coronal mass ejections(CMEs)-Sun particle emission-Sun solarterrestrial relations

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Sun-Earth connection event of super geomagnetic storm on 2001 March 31:the importance of solar wind density

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Research in Astronomy and Astrophysics 2020年第3期20卷 122-128页

作者： Li-Bin Cheng Gui-ming Le ming-xian zhao School of Physics and Electronic Information Shangrao Normal UniversityShangrao 334001China National Center for Space Weather China Meteorological AdministrationBeijing 100081China

An X1.7 flare at 10:15 UT and a halo CME with a projected speed of 942 km s-1 erupted from NOAA solar active region 9393 located at N20 W19,which were observed on 2001 March *** the CME reached the Earth,it triggered a super geomagnetic storm(hereafter super storm).We find that the CME always moved towards the Earth according to the intensity-time profiles of protons with different *** solar wind parameters responsible for the main phase of the super storm occurred on 2001 March 31 are analyzed while taking into account the delayed geomagnetic effect of solar wind at the L1 point and using the SYM-H *** to the variation properties of SYM-H index during the main phase of the super storm,the main phase of the super storm is divided into two parts.A comparative study of solar wind parameters responsible for two parts shows the evidence that the solar wind density plays a significant role in transferring solar wind energy into the magnetosphere,besides the southward magnetic field and solar wind speed.

关键词： Sun coronal mass ejections(CMEs)-Sun solar-terrestrial relations--Sun solar wind

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Properties of the Main Phases of the Super Geomagnetic Storms(ΔSYM-H≤-250 nT)with Different Heliolongitudes

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Research in Astronomy and Astrophysics 2023年第1期23卷 76-82页

作者： ming-xian zhao Gui-ming Le Yong-Hua Liu Key Laboratory of Space Weather National Satellite Meteorological Center(National Center for Space Weather)China Meteorological AdministrationBeijing 100081China School of Physics Science&Technology Lingnan Normal UniversityZhanjiang 524048China Innovation Center for FengYun Meteorological Satellite(FYSIC) Beijing 100081China CAS Key Laboratory of Solar Activity National Astronomical ObservatoriesBeijing 100101China Polar Research Institute of China Shanghai 200136China

We studied the properties of the main phases of 24 super geomagnetic storms(SGSs)(ΔSYM-H≤-250 nT)since *** divided the SGSs into two subgroups:SGSs-Ⅰ(-400 nT<ΔSYM-H≤-250 nT)and SGSs-Ⅱ(ΔSYM-H≤-400 nT).Of the 24 SGSs,16 are SGSs-Ⅰand eight are SGSs-Ⅱ.The source locations of SGSs were distributed in the longitudinal scope of[E37,W66].95.8%of the SGSs were distributed in the longitudinal scope of[E37,W20].East and west hemispheres of the Sun had 14 and 10 SGSs,*** durations of the main phases for six SGSs ranged from 2 to 4 *** durations of the main phases for the rest 18 SGSs were longer than 6.5 *** duration of the SGSs with source locations in the west hemisphere varied from 2.22 to 19.58 *** duration for the SGSs with the source locations in the east hemisphere ranged from 2.1 to31.88 *** averaged duration of the main phases of the SGSs in the west and east hemispheres are 8.3 hr and13.98 hr,respectively.|ΔSYM-H/Δt|for six SGSs with source locations distributed in the longitudinal area ranging from E15 to W20 was larger than 1.0 nT·minute^(-1),while|ΔSYM-H/Δt|for the rest 18 SGSs was lower than 1.0 nT·minute^(-1).|ΔSYM-H/Δt|for SGSs-Ⅰvaried from 0.18 to 3.0 nT·minute^(-1).|ΔSYM-H/Δt|for eight SGSs-Ⅱvaried from 0.37 to 2.2 nT·minute^(-1)with seven SGSs-Ⅱfalling in the scope from 0.37 to0.992 nT·minute^(-1).

关键词： The Sun-(Sun:)solar-terrestrial relations-(Sun:)solar wind

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Investigation of the possible source for the solar energetic particle event on 2017 September 10

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Research in Astronomy and Astrophysics 2018年第7期18卷 1-10页

作者： ming-xian zhao Gui-ming Le Yu-Tian Chi Key Laboratory of Space Weather National Center for Space WeatherChina Meteorological AdministrationBeijing 100081China School of Computer Science Anhui University of TechnologyMa'anshan 243032China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China

According to the solar proton data observed by Geostationary Operational Environmental Satellites （GOES）, ground-based neutron monitors on Earth and near-relativistic electron data measured by the ACE spacecraft, the onset times of protons with different energies and near-relativistic electrons have been estimated and compared with the time of solar soft and hard X-ray and radio burst data. The results show that first arriving relativistic and non-relativistic protons and electrons may have been accelerated by the concurrent flare. The results also suggest that release times of protons with different energies may be different, and the protons with lower energy may have been released earlier than those with higher energy. Some protons accelerated by concurrent flares may be further accelerated by the shock driven by the associated CME.

关键词： Sun coronal mass ejections (CMEs) - Sun flares - Sun particle emission

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What Can We Learn from the Geoeffectiveness of the Magnetic Cloud on 2012 July 15–17?

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Research in Astronomy and Astrophysics 2022年第1期22卷 14-18页

作者： Gui-Ang Liu ming-xian zhao Gui-ming Le Tian Mao School of Physics Science and Technology Lingnan Normal UniversityZhanjiang 524048China Key Laboratory of Solar Activity National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Key Laboratory of Space Weather National Center for Space WeatherChina Meteorological AdministrationBeijing100081China

An interplanetary shock and a magnetic cloud(MC) reached the Earth on 2012 July 14 and 15 one after *** shock sheath and the MC triggered an intense geomagnetic *** find that only small part of the MC from06:45 UT to 10:05 UT on 2012 July 15 made contribution to the intense geomagnetic storm,while the rest part of the MC made no contribution to the intense geomagnetic *** averaged southward component of interplanetary magnetic field(Bs) and duskward-electric fields(Ey) within the MC from 10:05 UT,2012 July 15 to09:08 UT,2012 July 16(hereafter MC2),are 15.11 nT and 8.01 my m-1,*** to the empirical formula established by Burton et al.(hereafter Burton equation),the geoeffectiveness of MC2 should be-655.42 nT,while the geoeffectiveness of MC2 is-324.68 nT according to the empirical formula established by O’Brien & McPherron(hereafter OM equation).However,the real geoeffectiveness of MC2 is 39.74 *** results indicate that the Burton equation and the OM equation cannot work *** geoeffectiveness of MC2 shows that large and long duration of Bs or Ey cannot guarantee the occurrence of an intense geomagnetic storm if the solar wind dynamic pressure is very *** we use 0.52 as γ,the geoeffectiveness of MC2 is 40.36 nT according to the empirical formula established by Wang et al.,which is very close to the observed value,indicating that the empirical formula established by Wang et *** much better than the Burton equation and the OM equation.

关键词： Solar coronal mass ejections Solar-terrestrial interactions Solar wind

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Effects of Offline Relaxation Quenching on Microstructure and Mechanical Properties of a Newly Designed High Performance Steel

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Journal of Iron and Steel Research International 2014年第4期21卷 459-463页

作者： Wen-zhen XIA xian-ming zhao Xiao-ming ZHANG Di WU State Key Laboratory of Rolling and Automation Northeastern University

The newly designed high performance tested steel was prepared by the process of vacuum induction furnace smelting and forging. According to the ideas of online relaxation and quenching intercritieal quenching-tempering （Q- L-T） process, effects of offline relaxation process on microstructure and mechanical properties of the tested steel were investigated. Offline results process was simulated using the MMS-300 thermal simulation testing apparatus and heat treating furnace. The results show that the microstructures are composed of bainite and martensite when the specimens are quenched in the austenite region. Once the specimens are ai〉cooled into the dual phase region, ferrite and granular bainite start to form. In the relaxation process, fine Nb（C, N） carbonitrides are precipitated first and then grow and coarsen. The microstructure is affected by process and determines mechanical properties. The Vickers hardness and yield strength （YS） first rise then fall when the relaxation temperature drops in austenite region, and then decline dramatically in dual phase region. When the relaxation time is 20 s, the tensile strength reaches the peak （1034 MPa）, and at that time YS is 872 MPa, elongation is 17.7% and Charpy V-notch impact energy is 171 J at -20℃. When the relaxation time increases to 100 s, the yield and tensile strengths are 750 and 934 MPa respectively, elon- gation is 18.6% and Charpy V-notch impact energy is 165 J at -20℃.

关键词： high performance steel offline relaxation process microstrueture mechanical property

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Effect of Air Pressure on Hardened Layer of U75V 60 kg/m Heavy Rail after Heat Treatment

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Journal of Harbin Institute of Technology(New Series) 2013年第1期20卷 52-56页

作者： Hao Kang xian-ming zhao Di Wu State Key Lab of Rolling and Automation Northeastern University

The samples cut from U75V 60 kg/m heavy rail are heated to 900 ℃ in resistance furnace and then put into air spraying channel to be cooled for 80 s, and change air pressure from 0.16 MPa to 0.33 MPa, and observe the effect of air pressure on hardened layer. The thickness and hardness of hardened layer increases with the increase of air pressure, and the thickness is more than 24 mm at the center and top fillets of rail head, and more than 15 mm at the blow fillets of rail head when air pressure is more than 0.26 MPa. During the tempering after heat treatment, tempering temperature of rail head is more than 570 ℃ when air pressure is separately 0.16 MPa, 0.20 MPa and 0.23 MPa, which is higher than finishing temperature of pearlite transformation at the cooling rate of 3 ℃/s according to CCT curve of U75V steel. When air pressure is separately 0.26, 0.30 and 0.33 MPa, the tempering temperature is 529 ℃ lower than finishing temperature of pearlite transformation at the cooling rate of 3 ℃/s. Under this condition, pearlite transformation is finished totally, so in order to reduce air consumption and control the cost, proper air pressure for U75V 60 kg/m heavy rail heat treating should be 0.26 MPa; the cooling rate increases with the increase of air pressure, and the average cooling rate on the surface of rail head is more than 3.21 ℃/s when air pressure is more than 0.26 MPa, and the largest cooling rate occurs at the top fillets of rail head.

关键词： air pressure hardened layer heavy rail heat treatment

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Extreme space weather events caused by super active regions during solar cycles 21-24

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Research in Astronomy and Astrophysics 2021年第5期21卷 296-300,302页

作者： Gui-ming Le Gui-Ang Liu ming-xian zhao Tian Mao Ping-Guo Xu School of Physics Science&Technology Lingnan Normal UniversityZhanjiang 524048China Key Laboratory of Space Weather National Center for Space WeatherChina Meteorological AdministrationBeijing 100081China Beijing Engineering Research Center of Smart Mechanical Innovation Design Service Beijing 100020China

Extreme space weather events including≥X5.0 flares,ground level enhancement(GLE)events and super geomagnetic storms(Dst≥-250 nT)caused by super active regions(SARs)during solar cycles 21-24 were *** total number ofX5.0 solar flares was 62,among which 41 were X5.0-X9.9 flares and 21 were≥X10.0 *** found that 83.9%of the≥X5.0 flares were produced by SARs;78.05%of the X5.0-X9.9 and 95.24%of the≥X10.0 solar flares were produced by SARs;46 GLEs were registered during solar cycles 21-24,and 25 GLEs were caused by SARs,indicating that 54.3%of the GLEs were caused by SARs;24 super geomagnetic storms were recorded during solar cycles 21-24,and 12 of them were caused by SARs,namely 50%of the super geomagnetic storms were caused by *** ascertained that only 29 SARs produced≥X5.0 flares,15 SARs generated GLEs and 10 SARs triggered super geomagnetic *** the 51 SARs,only 33 SARs produced at least one extreme space weather event,while none of the other 18 SARs could trigger an extreme space weather *** were only four SARs and each of them generated not only a≥X5.0 flare,but also a GLE event and a super geomagnetic *** of the extreme space weather events caused by the SARs appeared during solar cycles 22 and 23,especially for GLE events and super geomagnetic *** longitudinal distributions of source locations for the extreme space weather events caused by SARs were also studied.

关键词： Sun:sunspots Sun:flares Sun:particle emission Sun:solar-terrestrial relations

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Effects of Quenching Process on Microstructure and Mechanical Properties of Low Carbon Nb-Ti Microalloyed Steel

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Journal of Harbin Institute of Technology(New Series) 2013年第4期20卷 73-77页

作者： Wen-Zhen Xia xian-ming zhao Xiao-ming Zhang Di Wu State Key Laboratory of Rolling and Automation Northeastern University

The low carbon Nb-Ti mieroalloyed tested steel was prepared by the process of vacuum induction furnace smelting, forging and hot rolling. The new steel aims to meet the demand of high strength, high toughness and high plasticity for building facilities. The effects of quenching process on microstructure and mechanical properties of tested steel were investigated. The results showed that prior austenite grain size, phase type and precipitation behavior of （ Nb, Ti）（ C, N） play important roles in mechanical properties of the steel. Through modified appropriately, the model of austenite grain growth during heating and holding is d^5.7778 = 5. 6478^5.7778 ＋ 7.04 × 10^22t^1.6136 exp（- 427. 15 ×10^3 /（RT））. The grain growth activation energy is Qg = 427. 15 kJ. During quenching, the microscopic structures are mainly martensite and lath bainite which contains lots of lath substructure and dislocations. The content of phases, fine and coarsening （ Nb, Ti ）（ C, N ） precipitated changes during different quenching temperatures and holding time. Finally compared with the hardness value, the best quenching process can be obtained that heating temperature and holding time are 900 ℃ and 50 mins, respectively.

关键词： low carbon Nb-Ti mieroalloyed steel quenching process austenite grain growth model microstructure and mechanical properties

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Correlation of isothermal bainite transformation and austenite stability in quenching and partitioning steels

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Journal of Iron and Steel Research International 2017年第11期24卷 1095-1103页

作者： Shan Chen Guang-zhen Wang Chun Liu Chen-chong Wang xian-ming zhao Wei Xu State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina

The possible decomposition of metastable austenite during the partitioning process in the high end quenching and partitioning （Q＆P） steels is somewhat neglected by most researchers. The effects of primary martensite and alloying elements including manganese, cobalt and aluminum on the isothermal decomposition of austenite during typical Q＆P process were studied by dilatometry. The transformation kinetics was studied systematically and resulting microstruc tures were discussed in details. The results suggested that the primary martensite decreased the incubation period of isothermal decomposition by accelerating the nucleation process owing to dislocations especially on phase and grain boundaries. This effect can be eliminated by a flash heating which recovered dislocations. Co addition significantly promoted the bainite transformation during partitioning while A1 and Mn suppressed the isothermal bainite transformation. The bainite transformation played an important role in carbon distribution during partitioning, and hence the amount and stability of austenite upon final quenching. The bainite transformation during partitioning is an important factor in optimizing the microstructure in Q＆P steels.

关键词： Bainit e transformation Isothermal decomposition Retained austenite Quenching and partitioning steel Carbon partitioning

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