地球磁场的物理问题

地磁学的发展经历了两千多年的历史，文章回顾了这一漫长历史的四个主要阶段，对每一阶段研究的基本物理问题和主要进展做了简要概述．地磁场的空间分布、地磁场起源、地磁场长期变化和西向漂移、磁极移动和极性倒转、地磁场与人类生存环境等，是地磁学的基本物理问题．文章还从物理概念、研究现状和地磁学以及相关学科当前存在的问题等几个方面对地磁学未来的发展趋势做了简要的说明．     

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     

Global characteristics of the second-order ionospheric delay error using inversion of electron density profiles from COSMIC occultation data

It is a well known fact that ionospheric delay error is a predominant factor which influences the positioning accuarcy of GNSS.Although the main part of the first-order ionospheric delay error can be removed by the frequency-dependent behaviors of the ionosphere,the second-order ionospheric delay error must be eliminated to achieve millimetre-scale positioning accuracy.Due to COSMIC occultation providing electron density profiles on the global scale,the paper presents the first-order and the second-order ionospheric delay error analysis on the global scale using the inversion of electron density profiles from COSMIC occultation data during 2009–2011.Firstly,because of the special geographical location of three ISR(incoherent scatter radar),the first-order and the second-order ionospheric delay errors are calculated and discussed;the paper also shows and analyzes the diurnal,seasonal,semi-annual variation of ionospheric delay error with respect to signal direction.Results show that for the L1 signal path,the first-order ionospheric delay error is the largest near the equator,which is circa 7 m;the maximum second-order ionospheric delay error are circa 0.6 cm,0.8 cm and 0.6 cm respectively for L1 signals coming from the zenith,the north and the south at 10 degree elevation angles.The second-order ionospheric delay error on the L1 signal path from zenith are the symmetry between 15°and 15°with respect to magnetic equator,and are nearly zero at the magnetic equator.For the first time,the second-order ionospheric delay error on the global scale is presented,so this research will greatly contribute to analysing the higher-order ionospheric delay error characteristics on the global scale.     

光磁共振实验中抵消地磁场垂直分量的方法

介绍了光磁共振实验装置的各磁场线圈,分析了光磁共振实验中抵消地磁场垂直分量传统方法的缺陷,利用垂直磁场对磁共振信号的影响,提出了一种重复性较好的抵消地磁场垂直分量的方法,减小了传统实验方法产生的误差.这种方法也可用于测量地磁场垂直分量的大小.     

地球变化磁场Z分量的混沌动力学特性分析

对地球变化磁场进行了混沌动力学特性分析,主要进行了以下两个方面的工作:1)运用多种方法对多个地磁台站同一时段变化磁场分量数据(分为磁扰较小和磁扰较大时段)进行了混沌特性分析,主要是为了以更充分的判据来验证地球变化磁场是否具有混沌特性;2)同一地磁台站不同时段变化磁场分量数据的混沌特性分析,主要是验证地球变化磁场是否具有变参数混沌特性.分析结果表明:1)变化磁场时间序列确实具有混沌特性;2)从混沌时间序列相空间重构的角度可初步认为模拟地球变化磁场动力学系统所必须的独立变量应该为6左右;3)变化磁场时间序列不仅具有混沌特性而且其参数也是在缓慢变化着的,具有变参数混沌系统的特性.     

RBLs与XBLs的多波段流量及中心黑洞质量的研究

BL Lacs天体的辐射谱变化、多波段的相关性及偏振的特性为研究各辐射分量的内禀相互关联提供重要的信息.本文用收集了RBLs和XBLs的红移、中心黑洞质量,统计得到RBLs天体的红移大于XBLs天体,RBLs天体的平均中心黑洞质量小于XBLs天体的平均中心黑洞质量.本文还收集了低态时射电波段、红外波段、光学波段及X射线波段的辐射流量,并分析了它们之间的相关性,及其与红移的相关性.本文的结果支持了RBLs和XBLs可作为BL Lac天体的有效分类标准的观点,并且表明它们的物理性质可能存在差异,而非选择效应的 关键词： BL Lac天体 多波段辐射流量     

螺旋型爆磁压缩脉冲发生器电阻及磁通损失的数值计算

基于电流和磁扩散方程,讨论了螺旋型爆磁压缩脉冲发生器(MFCG) 中的电阻与磁通损耗问题,将相关的接触电阻模型、欧姆电阻的趋肤效应与邻近效应模型具体应用到2维爆轰磁流体力学程序MFCG-Ⅳ中,进一步完善了程序的物理功能。并选用美国德克萨斯理工大学简单绕制的螺旋型爆磁压缩脉冲发生器的实验结果对新增模块进行了考证,计算结果符合物理规律,且与实验测量吻合较好。     

螺旋型爆磁压缩脉冲发生器电阻及磁通损失的数值计算

基于电流和磁扩散方程,讨论了螺旋型爆磁压缩脉冲发生器(MFCG)中的电阻与磁通损耗问题,将相关的接触电阻模型、欧姆电阻的趋肤效应与邻近效应模型具体应用到2维爆轰磁流体力学程序MF-CG-Ⅳ中,进一步完善了程序的物理功能。并选用美国德克萨斯理工大学简单绕制的螺旋型爆磁压缩脉冲发生器的实验结果对新增模块进行了考证,计算结果符合物理规律,且与实验测量吻合较好。     

Uncovering the underlying physical mechanisms of biological systems via quantification of landscape and flux

In this review, we explore the physical mechanisms of biological processes such as protein folding and recognition,ligand binding, and systems biology, including cell cycle, stem cell, cancer, evolution, ecology, and neural networks. Our approach is based on the landscape and flux theory for nonequilibrium dynamical systems. This theory provides a unifying principle and foundation for investigating the underlying mechanisms and physical quantification of biological systems.     

利用磁聚焦法测量地磁场的研究

利用电子比荷测试仪,配合数字万用表,采用正、反向两次励磁电流聚焦方法测出地磁场的水平分量和垂直分量,进一步确定出地磁场的大小和方向.     

Design of square-shaped heat flux cloaks and concentrators using method of coordinate transformation

A square-shaped heat flux cloak and a square-shaped heat flux concentrator have been designed theoretically according to the invariance symmetry of steady state thermal conductive equation. The direction of heat flux in these devices can be modulated as desired. Using the method of coordinate transformation, the inhomogeneous and anisotropic thermal conductivity in the transformation region have been acquired. Two-dimensional finite element simulations were performed to confirm the theoretical results.     

Effect of NO concentration disturbances on the global distribution of ionospheric parameters during geomagnetic storms

The role of nitric oxide (NO) in the ionospheric effects during geomagnetic storm on May 1–3, 2010, is examined. The studies are performed using a global self-consistent model of the thermosphere, ionosphere and protonosphere (GSM TIP). Two versions of calculations are used: (1) based on an analytical approximation of the NO concentration and (2) self-consistent calculation of the global distribution of nitric oxide over the ionosphere. It is shown that, during a geomagnetic disturbance, the NO concentration at high latitudes shows an increase, which under the influence of the horizontal circulation of neutral gas leads to an increase in the concentration of NO at mid-latitudes ～1 day after the start of the perturbation. Simulated values of foF2 are compared to experimental data obtained at a number of Russian mid-latitude stations. It is noted that the self-consistent calculations of the NO concentration better describes the spatial-temporal behavior of ionospheric parameters during geomagnetic storms.     

Ground states and flux configurations of the two-dimensional Falicov-Kimball model

The Falicov-Kimball model is a lattice model of itinerant spinless fermions (electrons) interacting by an on-site potential with classical particles (ions). We continue the investigations of the crystalline ground states that appear for various filling of electrons and ions for large coupling. We investigate the model for square as well as triangular lattices. New ground states are found and the effects of a magnetic flux on the structure of the phase diagram are studied. The flux phase problem where one has to find the optimal flux configurations and the nuclei configurations is also solved in some cases. Finally we consider a model where the fermions are replaced by hard-core bosons. This model also has crystalline ground states. Therefore their existence does not require the Pauli principle, but only the on-site hard-core constraint for the itinerant particles.     

Controlled decoherence of floating flux qubits

In Born-Markov approximation,this paper calculates the energy relaxation time T 1 and the decoherence time T 2 of a floating flux qubit by solving the set of Bloch-Redfield equations.It shows that there are two main factors influencing the floating flux qubits:coupling capacitor in the circuit and the environment resistor.It also discusses how to improve the quantum coherence time of a qubit.Through shunt connecting/series connecting inductive elements,an inductive environment resistor is obtained and further the reactance component of the environment resistor is improved,which is beneficial to the enhancement of decoherence time of floating flux qubits.     

The initial decoherence of the mesoscopic Josephson junction flux qubit

For a mesoscopic radio frequency superconducting quantum interference device (rfSQUID), at a degeneracy point, the system reduces to a quantum two-state system which can be used as a flux qubit. When the noise environment is equivalent to a harmonic oscillators bath, by virtue of an operator-norm measure for the short time decoherence, this paper investigates the initial decoherence of the flux qubit operating in the ohmic noise environment and illustrates its property by means of the numerical evaluation.     

强降水过程中垂直螺旋度和散度通量及其拓展形式的诊断分析

在垂直螺旋度的基础上,定义了散度通量,水汽垂直螺旋度和水汽散度通量三个宏观物理量.针对两次强降水过程,利用NCEP/NCAR实时分析资料对这些物理量进行诊断分析,结果表明,这些物理量能够比较准确地综合表征强降水系统所共有的典型动力场垂直结构,进而与降水系统的发展演变密切相关.这些物理量垂直积分的异常值区与观测的6 h累积地面降水具有良好的对应关系,表明它们对强降水的落区和降水系统的发展移动具有良好的指示预测意义.NCEP-GFS每日四次6 h预报场资料的计算表明,垂直螺旋度和散度通量及其拓展形式（水汽垂直 关键词： 垂直螺旋度 散度通量 水汽垂直螺旋度 水汽散度通量     

Effect of the Aharonov-Bohm flux on the magnetic gap soliton in antiferromagnetic chain

Employing the double-sublattice, the coherent state ansatz, and the time-dependent variational principle, we have studied the effects of the Aharonov-Bohm flux on the soliton in one-dimensional antiferromagnetic chain. The results show that the Aharonov-Bohm flux have an effect on the peak, the width, the energy and the spatial configuration of the spin of the soliton.     

On gravitational radiation and the energy flux of matter

A suitable derivative of Einstein's equations in the framework of the teleparallel equivalent of general relativity (TEGR) yields a continuity equation for the gravitational energy‐momentum. In particular, the time derivative of the total gravitational energy is given by the sum of the total fluxes of gravitational and matter fields energy. We carry out a detailed analysis of the continuity equation in the context of Bondi and Vaidya's metrics. In the former space‐time the flux of gravitational energy is given by the well known expression in terms of the square of the news function. It is known that the energy definition in the realm of the TEGR yields the ADM (Arnowitt‐Deser‐Misner) energy for appropriate boundary conditions. Here we show that the same energy definition also describes the Bondi energy. The analysis of the continuity equation in Vaidya's space‐time shows that the variation of the total gravitational energy is determined by the energy flux of matter only.     

On the dynamics created by a time-dependent Aharonov-Bohm flux

We study the dynamics of classical and quantum particles moving in a punctured plane under the influence of a homogeneous magnetic field and driven by a time-dependent singular flux tube through the hole.