基于射电观测的日冕物质抛射驱动激波的统计特征研究

本文基于Wind/WAVES和STEREO/SWAVES等多卫星射电观测资料,选择第24太阳活动周2007年1月至2015年12月期间77个Ⅱ型射电暴样本事件,拟合其激波速度,分析了激波参数与日冕物质抛射(CME)、耀斑和太阳高能粒子(SEP)等参数的相关关系及变化规律,并探讨了射电增强对这些关系的影响.研究结果显示:1)在Ⅱ型射电暴十米百米(DH)波段范围起始时刻,激波高度比CME前沿高度略高一点,即激波脱体距离(standoff distance)约0.4 Rs,且这个高度随CME向外传播而增大.在低日冕和高日冕,激波脱体距离随CME速度的变化呈现明显相反的规律;在低高度上, CME速度快,激波脱体距离大,而在高高度上, CME速度慢,脱体距离大. 2)射电增强伴随事件的CME速度明显大于无射电增强事件;射电增强伴随事件的激波速度与CME质量、动能的相关性明显好于无射电增强伴随事件. 3)有射电增强伴随的Ⅱ型射电暴DH波段持续时间与CME速度、质量、动能之间无明显相关性,而无射电增强事件的DH波段持续时间与这三个量之间呈正相关. 4)产生SEP事件的激波速度明显大于未产生SEP事件的激波速度;有射电增强伴随的Ⅱ型射电暴(激波)事件产生SEP事件的比例略高于无射电增强事件(73.5% 67.4%),但射电增强事件产生大SEP事件(large SEP event)的比例(67.6%)明显高于无射电增强事件(37.2%).进一步表明, Ⅱ型射电暴射电增强可作为其驱动源(激波)大概率产生大SEP事件的辨别信号之一.     

日冕物质抛射引起地磁扰动的分类预报

对1997—2003年期间引起地磁扰动的72个加速日冕物质抛射(CME)事件和69个减速CME事件进行了特性分析，并针对经行星际闪烁(IPS)认证的32个加速CME引起的地磁扰动事件和32个减速CME引起的地磁扰动事件分类建立了新的从属函数μ_T和新的磁扰开始时间修正项, 经验证预报效果得到显著提高.对于加速CME引起的地磁扰动事件，磁扰开始时间的预报值T_pre与观测值T_obs比较，相对误差ΔT_pre/T_obs≤10%的事件占总事件数的21.86%；ΔT_pre/T_obs≤30%的事件为78.13%；而ΔT_pre/T_obs>50%的事件为9.36%；对于减速CME引起的地磁扰动事件相对误差ΔT_pre/T_obs≤10%的事件占总事件数的25.00%；ΔT_pre/T_obs≤30%的事件为84.37%；而ΔT_pre/T_obs>50%的事件仅为3.13%.这表明该预报方法对空间灾害性事件的磁扰动的定量预报具有很大的现实可能性. 关键词： 日冕物质抛射 地磁扰动 从属函数     

同轴圆柱系统微变问题的静电解

我们从一种较为特殊但又是十分典型的同轴结构的探讨开始,它的截面在极坐标系统中(原点置于轴心)具有 ρ_1=r_l(1+ε_1 cosnφ),ρ_2=r_2(1+ε_2cos(φ-φ_0))。 (1)其中r_1和r_2系变形前外的导体因截面半径;ε_1和ε_2则为表征其变形特点的小参数;φ_0表示相似变形后内外导体叉开的一个角度;而n为某一正整数。象这样的同轴系统,不妨形象化称为“n波”同轴系统。 我们知道,二维拉普拉斯方程的环内问题,在极坐标系统中的一般解可以用圆谐函数来组合:     

铁电单晶(K_xNa_(1-x))_(0.4)(Sr_yBa_(1-y))_(0.8)Nb_2O_6的光学性质和线性电光效应

本文介绍铁电单晶(K_xNa_(1-x))_(0.4)(Sr_yBa_(1-y))_(0.8)Nb_2O_6的光学性质和线性电光效应的测量。实验结果表明,这种晶体具有较大的光学双折射,透光范围由4000A到5.6μm。晶体具有低的线性电光调制的半波电压,其电光调制价值指数n_0~3·γ_c高达730×10~(-12)m/V,而激光损伤阈值为600MW/cm~2(4 pps),表明该晶体可作为较大功率激光调制使用的材料。     

Distinct Three-Level Spin–Orbit Control Associated with Electrically Controlled Band Swapping

We investigate the Rashba and Dressehaus spin-orbit(SO) couplings in an ordinary GaAs/AlGaAs asymmetric double well,which favors the electron occupancy of three subbands v=1,2,3.Resorting to an external gate,which adjusts the electron occupancy and the well symmetry,we demonstrate distinct three-level SO control of both Rashba(α_v) and Dresselhaus(β_v) intraband terms.Remarkably,as the gate varies,the first-subband SO parameters α_1 and β_1 comply with the usual linear behavior,while α_2(β_2) and α_3(β_3) respectively for the second and third subbands interchange the values,triggered by a gate controlled band swapping.This provides a pathway towards fascinating selective SO control in spintronic applications.Moreover,we observe that the interband Rashba(η_(μv)) and Dresselhaus(L_(μv)) terms also exhibit contrasting gate dependence.Our results should stimulate experiments probing SO couplings in multi-subband wells and adopting relevant SO features in future spintronic devices.     

在周期场中类氢原子的1s,2s,2p基态的能级

取1/Z/(me~2)为长度单位,Z~2(me~4/~2)为能量单位,则类氢原子的波函数ψ(r)满足 -1/2ψ-1/rψ=Eψ。 (1)在周期场中,采用Wigner-Seitz近似,以等体积原子球代替原子多面体,则在半径r_0处基态ψ满足边界条件(由ψ的周期性质和对称性质得到) (ψ/r)_r_0=0,对1s,2s; (2) (ψ)_r_0=0,对2p。(3) 根据严格的合流超几何函数的波函数,利用Slater的表和库伦波函数表,可以得到能量与原子球半径r_0的数值关系(见表1)。     

超音速绕流Mach-Zehnder干涉图分析的Abel变换

本文处理了含激波的柱对称或球对称抛射体超音速统流Mach-Zehnder干涉图分析的Abel变换问题。我们对一般的Abel积分方程研究了具有有限个间断点的解的某些性质;将其应用到Mach-Zehnder干涉图的干涉条纹移动δ(x)和密度ρ(x)间的Abel变换上,得到了三个有明显物理意义的结论,(1)干涉图上的任一直线上的干涉条纹移动δ(x)是x的连续函数;(2)若在截面1-1上的圆环r=c处有激波,则当x→c_时,δ’(x)～L/(c-x)~(1/2);(3)若除尖点c外,干涉条纹移动δ(x)是光滑的,limδ’(x)存在,且当x→c_时,δ’(x)～L/(c-x)~(1/2),则流场中于圆环r=c处出现激波,在激波两侧密度跳跃值为Δρ=λ*L/K(2c)~(1/2),且对r≥c和r相似文献   

Tripartite Entanglement Measures of Generalized GHZ State in Uniform Acceleration

Using the single-mode approximation,we study entanglement measures including two independent quantities;i.e.,negativity and von Neumann entropy for a tripartite generalized Greenberger-Horne-Zeilinger(GHZ)state in noninertial frames.Based on the calculated negativity,we study the whole entanglement measures named as the algebraic average π3-tangle and geometric average Π3-tangle.We find that the difference between them is very small or disappears with the increase of the number of accelerated qubits.The entanglement properties are discussed from one accelerated observer and others remaining stationary to all three accelerated observers.The results show that there will always exist entanglement,even if acceleration r arrives to infinity.The degree of entanglement for all 1-1 tangles are alwa.ys equal to zero,but 1-2 tangles always decrease with the acceleration parameter r.We notice that the von Neumann entropy increases with the number of the accelerated observers and Sκ_Ιζ_Ι(κ,ζ∈(A,B,C)) first increases and then decreases with the acceleration parameter r.This implies that the subsystem ρκΙζΙ is first more disorder and then the disorder will be reduced as the acceleration parameter r increases.Moreover,it is found that the von Neumann entropies SABCI,SABICI and SAIBICI always decrease with the controllable angle θ,while the entropies of the bipartite subsystems S2-2_(non)(two accelerated qubits),S2-1_(non)(one accelerated qubit) and S2-0_(non)(without accelerated qubit) first increase with the angle θ and then decrease with it.     

基于红/绿/蓝/青/黄/暖白6色LED的白光光谱优化方法

提出了一种基于脉冲宽度调制(PWM)的红/绿/蓝/青/黄/暖白(R/G/B/C/Y/WW)6色发光二极管(LED)的白光光谱优化方法。该方法根据光谱叠加性原理,采用1931 CIE-XYZ三刺激值建立了G+WW,B+C,R+Y各混合光源色坐标与光通量贡献率ρ_(G+WW)(r_1),ρ_(B+C)(r_2),ρ_(R+Y)(r_3)的函数关系,在不同光通量百分比r_1,r_2,r_3下,通过优化遍历范围计算得到相关色温为2700, 4000, 5500, 7000 K时合成白光的最优显色指数R_a为96.4,97.0,97.3,97.4,并采用R/G/B/C/Y/WW 6色LED进行实验验证。结果表明:R/G/B/C/Y/WW LED模块可实现相关色温在2700～7000 K范围内的白光调节。当光通量设定为500 lm时,相关色温的最大相对误差为1.96%,一般显色指数R_a最大相对误差为1.24%,发光效率可达146.81～152.40 lm·W~(-1)。     

轻原子和离子的多重态理论计算

本文的目的是探索一种参数比较少而计算结果又比较好的解析波函数来计算轻原子和离子的多重态能量,并与其他方法计算的结果和实验结果相比较。我们选用下列波函数: 1s电子:ψ_1(r):N_1e~(-μar)[1 (μbr)~1] 2s电子:ψ_2(r)=N_2[μr)e~(μr)-Ne~(μar)], 2p电子:ψ_3(r)=N_3(μr)cosθe~(-μr) ψ_4(r)=N_4(μr)sinθe~(1φ-μr) ψ_5(r)=N_5(μr)sinθe~(-1φ-μr) 计算了第二周期元素正常态原子和相应的离子的波函数的最佳参数值和能量值。这套波函数只有三个参数μ,a和b。结果表明理论计算的能量值与实验值符合得很好,误差在百分之一到千分之一的范固内。而且与Morse和Tubis等人过去用四参数波函数算出的结果很接近,有些还要好一些。说明我们选用的这套波函数是比较简单而又比较准确的。     

Quasiperiodic Variations of Solar Activity and Cosmic Rays

Quasiperiodic variations of various manifestations of solar activity, parameters of the interplanetary medium, and the flux of galactic cosmic rays (GCRs) are studied using the data of stratospheric sounding and measurements with neutron monitors. Groups of spectral components with periods of ~2, 1.3, and ~1 year are identified in the range of periods shorter than 5 years. Particular attention is paid to quasi-2-year GCR variations that are induced by similar variations of the mean magnetic field of the Sun and are integral to the processes of solar activity.     

Electrostatic Nonplanar Positron-Acoustic Shock Waves in Superthermal Electron-Positron-Ion Plasmas

The basic properties of the nonlinear propagation of the nonplanar(cylindrical and spherical) positronacoustic(PA) shock waves(SHWs) in an unmagnetized electron-positron-ion(e-p-i) plasma containing immobile positive ions,mobile cold positrons,and superthermal(kappa distributed) hot positrons and electrons are investigated both analytically and numerically.The modified Burgers equation(mBE) is derived by using the reductive perturbation method.The basic features of PA SHWs are significantly modified by the cold positron kinematic viscosity(η),superthermal parameter of electrons(κ_e),superthermal parameter of hot positrons(κ_p),the ratio of the electron temperature to hot positron temperature(σ),the ratio of the electron number density to cold positron number density(μ_e),and the ratio of the hot positron number density to cold positron number density(μ_(ph)).This study could be useful to identify the basic properties of nonlinear electrostatic disturbances in dissipative space and laboratory plasmas.     

Interaction of high-speed and transient fluxes of solar wind at the maximum of solar cycle 24

The interaction of the interplanetary coronal mass ejection (ICME) and the high-speed solar wind flux (HSSWF) associated with the coronal hole (CH) is considered. By the examples of two events at the maximum of solar cycle 24 from June 4 to June 16 and from June 30 to July 10, 2012 it is shown that the temperature-dependent parameters of the SW ionic composition appear closer to the values in the HSSWF than in the ICME due to mixing of fluxes in the corona when the ICME source is near the CH boundary.     

Explicit Relations of Physical Potentials Through Generalized Hypervirial and Kramers' Recurrence Relations

Based on a Hamiltonian identity,we study one-dimensional generalized hypervirial theorem,Blanchardlike(non-diagonal case) and Kramers'(diagonal case) recurrence relations for arbitrary x~κ which is independent of the central potential V(x).Some significant results in diagonal case are obtained for special κ in x~κ(κ≥ 2).In particular,we find the orthogonal relation(n_1|n_2) = δ_(n_1n_2)(κ = 0),(n_1|V'(x)\n_2) =(E_(n_1)-E_(n_2))~2〈n_1x|n_2)(κ = 1),E_n =(n/V'(x)x/2|n) +(n|V(x)|n)(κ = 2) and-4E_n(n|x|n) +(n|V'(x)x~2\n〉 +4〈n|V(x)x|n〉 = 0(κ = 3).The latter two formulas can be used directly to calculate the energy levels.We present useful explicit relations for some well known physical potentials without requiring the energy spectra of quantum system.     

The Pressure-Induced Spectral Shift Calculations for Seven Crystals with MgO,CaO, or α-A12O3 as the Hosts

The conception of expansion function ф(κ) at the exponential of d electron radial wavefunction of transition-metal cations developed in Refs. [1-5] was used to interpret pressure-induced spectral shifts of series of crystals. The red or blue shifts of the spectra of 4 crystals with MgO or CaO as hosts and 3 crystals with α-A1₂O₃ as hosts were calculated by making use of the parameters obtained from fitting the experimental spectral shifts of Mg0:Cr³⁺ and α-A1₂O₃:Cr³⁺ crystals respectively. The results are satisfactory, and it has been found that ф(κ) and η(κ) are mainly effected by the host while the difference of the impurity transition-metal ions causes ф(κ) and η(κ) varied only slightly.     

Extraction of Nuclear Matter Properties from Nuclear Masses by a Model of Equation of State

The extraction of nuclear matter properties from measured nuclear masses is investigated in the energy density functional formalism of nuclei.It is shown that the volume energy a1 and the nuclear incompressibility Ko depend essentially on μ_nN + μ_pZ - 2E_N,whereas the symmetry energy J and the density symmetry coefficient L as well as symmetry incompressibility Ks depend essentially on μ_n - μ_p,where μ_p ＝μp - ∂E_c/∂Z,μ_n and μ_p are the neutron and proton chemical potentials respectively,E_N the nuclear energy,and E_c the Coulomb energy.The obtained symmetry energy is J ＝ 28.5 MeV,while other coefficients are uncertain within ranges depending on the model of nuclear equation of state.     

准一维Cr基超导体RbCr3As3的超导能隙

RbCr₃As₃是具有[（Cr₃As₃）^-]_∞线性链的准一维超导体,超导转变温度约为6.6 K.对RbCr₃As₃单晶进行了电输运和极低温热输运性质的研究.低温下,拟合了RbCr₃As₃正常态电阻率随温度的变化,发现其满足费米液体行为.通过拟合超导转变温度随磁场的关系,得到RbCr₃As₃单晶的上临界场约为25.6 T.对RbCr₃As₃进行了零场下的极低温热导率测量,得到其剩余线性项为7.5 μW·K^-2·cm^-1,占正常态热导率值的24%.测量不同磁场下RbCr₃As₃的热导率,发现与单带s波超导体相比较,RbCr₃As₃剩余线性项随磁场增加相对较快.这些结果表明RbCr₃As₃单晶很可能是有节点的非常规超导体.     

Study of the relationship between coronal mass ejections and energetic electrons in interplanetary space

We consider time characteristics of energetic electron events in the interplanetary space after solar flares associated with coronal mass ejections (CME). Analysis of electron intensity-time profiles shows that independently of flare duration, times to electron event maximum from flare onset and from electron event onset increase with increasing of CME velocity. A possible interpretation of this effect is electron acceleration by CME associated with a shock wave.Published from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 1, pp. 46–52, January, 1996.This work was supported by the Russian Foundation for Fundamental Research (grant 94-02-04453) and by a Contract with EOARD (grant SPC-94-4071).     

坐标空间中构造的Breit夸克势与介子和夸克偶素的质量劈裂

构造夸克间的有效的相互作用势函数是强子物理中的重要研究课题,也是学科前沿问题之一.本文对坐标空间中的Breit夸克势函数的完整形式实施消除奇异因子的替代方法,构造出一个有效的夸克势.除了第一项库仑势和第七项常数项势,对其他的项都需进行重新构造,即对第二项和第四项做δ(r)→μ~3e~(-μr)/8π替代,对第三项做1/r→(1-e-μr)/r替代,对第五项和第六项做1/r~3→1-(1+μr)e~(-μr)/r~3替代,由此重新构造出新的势函数,然后用来计算质量劈裂,检验构造势的有效性.为此计算了一组含重介子和夸克偶素的质量劈裂.计算中屏蔽质量μ不是简单的常数,而是取与夸克质量m_i,m_j有关的变量.研究计算发现,只有当屏蔽质量μ取为关于夸克平均质量μ_a=(m_i+m_j)/2的洛朗级数形式μ=c_(-3)(μ_a+0.512)-3+c_(-2)(μ_a+0.512)~(-2)+c_(-1)(μ_a+0.512)~(-1)+c_0+c_1(μ_a+0.512)时重介子η_c-J/ψ,η_b-Υ(1s),还有χ_(c0)-χ_(c1)-χ_(c2)等的夸克偶素之间质量劈裂精确达到实验值,同时其他介子尤其是6个D介子质量精度都比以往得到较大幅度的改善.因此,本文构造出一个有效的夸克势模型.     

Response of auroral regions to directional changes of the interplanetary magnetic field: Case study

Summary On October 6, 1979, the low-altitude polar-orbiting satellites DMSP-F2 and-F4 crossed the auroral electron precipitation region in the opposite hemispheres at nearly the same universal time (UT) and in the same magnetic local-time (MLT) sector near midnight. Three pairs of such nearly simultaneous conjugate crossings took place during a period of enhanced magnetic activity and strongly turning northward or southward of the interplanetary magnetic field (IMF). These conjugate observations allowed the study, with time resolution better than six minutes, of the variation, in response to directional changes of the interplanetary magnetic field, of the latitudinal position and width of the auroral regions; these are believed to map the central plasma sheet (CPS) and boundary plasma sheet (BPS). During the equatorward expansion of the whole auroral electron precipitation region, its latitudinal width is observed to decrease markedly when the IMF turns from a northern to a southern direction. In particular, a different response of the equatorward boundary of the auroral oval with respect to the poleward boundary results from the observations, showing that the speed of the equatorward expansion of the equatorward boundary, measured at a temporal resolution of less than 6 minutes, is lower than the speed of the poleward boundary. The BPS/CPS boundary moves coherently with the southward turning of the IMF, with intermediate speed. It follows that the latitudinal width of the poleward part of the auroral region, assumed to map the boundary plasma sheet, decreases more dramatically than the width of the equatorward part of the region mapping the central plasma sheet. These findings could be explained in terms of changes of the total open magnetic flux. Actually, the equatorward shift of the poleward boundary of the auroral oval and the subsequent dramatic thining of the BPS region seem to be the consequence of a larger number of geomagnetic flux line interconnected with the IMF during a southward IMF condition.