Auroral electrojet dynamics during magnetic storms, connection with plasma precipitation and large-scale structure of the magnetospheric magnetic field

Effect of the equatorward shift of the eastward and westward electrojets during magnetic storms main phase is analyzed based on the meridional chains of magnetic observatories EISCAT and IMAGE and several Russian observatories (geomagnetic longitude ≈110°, corrected geomagnetic latitudes 74°>φ>51°.) Magnetic storms of various Dst index intensity where the main phase falls on 1000 UT - 2400 UT interval were selected so that one of the observatory chains was located in the afternoon - near midnight sector of MLT. The eastward electrojet center shifts equatorward with Dst intensity increase: when Dst ≈ −50 nT the electrojet center is located at φ ≈ 62°, when Dst ≈ −300 nT it is placed at φ ≈ 54°. The westward electrojet center during magnetic storms main phase for intervals between substorms shifts equatorward with Dst increase: at φ ≈ 62° when Dst ≈ −100 nT and at φ ≈ 55° when Dst ≈ −300 nT. During substorms within the magnetic storms intervals the westward electrojet widens poleward covering latitudes φ ≈ 64°–65°. DMSP (F08, F10 and F11) satellite observations of auroral energy plasma precipitations at upper atmosphere altitudes were used to determine precipitation region structure and location of boundaries of various plasma domains during magnetic storms on May 10–11, 1992, February 5–7 and February 21–22, 1994. Interrelationships between center location, poleward and equatorward boundaries of electrojets and characteristic plasma regions are discussed. The electrojet center, poleward and equatorward boundaries along the magnetic observatories meridional chain were mapped to the magnetosphere using the geomagnetic field paraboloid model. The location of auroral energy oxygen ion regions in the night and evening magnetosphere is determined. Considerations are presented on the mechanism causing the appearance in the inner magnetosphere during active intervals of magnetic storms of ions with energy of tens KeV. In the framework of the magnetospheric magnetic field paraboloid model the influence of the ring current and magnetospheric tail plasma sheet currents on large-scale magnetosphere structure is considered.     

Magnetopause boundary structure deduced from the high-time resolution particle experiment on the Equator-S spacecraft

An electrostatic analyser (ESA) onboard the Equator-S spacecraft operating in coordination with a potential control device (PCD) has obtained the first accurate electron energy spectrum with energies &7 eV-100 eV in the vicinity of the magnetopause. On 8 January, 1998, a solar wind pressure increase pushed the magnetopause inward, leaving the Equator-S spacecraft in the magnetosheath. On the return into the magnetosphere approximately 80 min later, the magnetopause was observed by the ESA and the solid state telescopes (the SSTs detected electrons and ions with energies &20–300 keV). The high time resolution (3 s) data from ESA and SST show the boundary region contains of multiple plasma sources that appear to evolve in space and time. We show that electrons with energies &7 eV–100 eV permeate the outer regions of the magnetosphere, from the magnetopause to &6Re. Pitch-angle distributions of &20–300 keV electrons show the electrons travel in both directions along the magnetic field with a peak at 90° indicating a trapped configuration. The IMF during this interval was dominated by Bx and By components with a small Bz.     

原子折射度与电子构型的关系

原子折射度与其电子构型密切相关。元素在周期表中按最外层电子数可分为s、p、sd、df4个区,原子折射度的变化在各个区内是不同的。原子折射度可表示为主量子数及最外层电子数的函数,根据这个函数计算出来的值与文献给出的值十分吻合。     

The Inverse Problem for Collinear Central Configurations

We consider the problem: given a collinear configuration of n bodies, find the masses which make it central. We prove that for n ≤ 6, each configuration determines a one-parameter family of masses (after normalization of the total mass). The parameter is the center of mass when n is even and the square of the angular velocity of the corresponding circular periodic orbit when n is odd. The result is expected to be true for any n. This revised version was published online in July 2006 with corrections to the Cover Date.     

高压变电站抗震-可靠性分析(二)

在双母线系统抗震可靠性分析的基础上,进一步讲座了高为电站另一种重要接线形式－双母线带旁路母线接线系统的抗震可靠性分析问题,针对双母线带旁路母线接线系统具有储备系统的特点,建立了具有备用系统情形的抗震可靠性分析方法,同时给出了在各个抗震可靠性分析准则条件下接线系统的抗震可靠性。     

Tokamak residual zonal flow level in near-separatrix region

Residual zonal flow level is calculated for tokamak plasmas in the near-separatrix region of a diverted tokamak. A recently developed method is used to construct an analytic divertor tokamak configuration. It is shown that the residual zonal flow level becomes smaller but still keeps finite near the separatrix because the neoclassical polarisation mostly due to the trapped particles goes larger in this region.     

基于GML的地理信息发布系统的安全防护研究

GML是构建地理信息发布系统的一种工具,在当前广泛采用的以Browser/Server方式开发的3层体系结构的地理信息发布系统中得到了极大的应用。但这种以GML为应用策略的地理信息发布系统存在着一定的安全隐患。此处分析了这种安全隐患,把主动防御的思想应用到地理信息发布系统的安全防护框架中,分别说明了安全防护、入侵检测、攻击响应、事故恢复等子系统在地理信息发布系统安全防护中所起的作用。     

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Characteristics of an Explosive Cyclone over Northeast China Revealed by Satellite Water Vapor Imagery

In this paper, an explosive cyclone(EC) that occurred over Northeast China in the spring of 2016 is studied by using 6.7 μm FY satellite water vapor(WV) imagery and NCEP(1°×1°) reanalysis data. Moreover, the evolutions of the upper-level jet stream(ULJ), the vertical motions, and the potential vorticity(PV) are analyzed in detail. Results show that different shapes of the WV image dark zones could reflect different stages of the EC. At the pre-explosion stage, a small dark zone and an S-shaped b...     

基于最大熵模型的深圳市内涝影响因素分析及内涝风险评估

城市内涝是最常见的自然灾害之一,深入剖析其影响因素并进行风险评估对内涝防治具有重要意义。以往研究表明,城市内涝是由自然因素(如地形)和人为因素(如土地利用)共同引起的。在土地利用方面,相关学者主要关注二维空间因素对内涝的影响,较少顾及土地利用的三维建筑格局。此外,在研究方法的选取上,尽管已有学者利用随机森林、神经网络等模型对内涝影响因素进行研究,然而传统方法在负样本(不发生内涝的地点)的选取上存在不确定性。为解决这2点不足,论文引入最大熵(MAXENT)模型,以深圳市为研究案例,通过MAXENT剖析各潜在影响因子与内涝风险的关系。结果表明,影响内涝风险的主导环境因子为不透水面比例、绿地比例、人口密度、暴雨峰值雨量、地表起伏度。而对内涝发生有重要影响的三维因子为容积率、建筑形状系数、平均高度。通过MAXENT评估的内涝风险结果可知,深圳潜在高风险区的面积约为491 km²,占市域面积的24.58%,主要位于龙华区、南山区、龙岗区北部、光明区、福田区。进一步对潜在高风险区进行空间自相关分析,结果发现过往并不存在内涝点的南山区北部、福田区西部、罗湖区中部等部分区域风险概...