COSMIC掩星电离层资料反演以及结果验证

通过COSMIC掩星电离层观测资料L1和L2相位组合,得到相对总电子含量TEC;利用非掩星的辅助观测数据校正TEC,消除LEO卫星高度以上的TEC部分;在电子密度局部球对称假设和信号直线传播的近似下,通过Abel积分变换可以得到电子密度垂直廓线.将2007年度中与电离层测高仪站点经度差小于10°,纬度差小于2°的4903个COSMIC掩星电离层资料与相对应的电离层测高仪数据进行比较,F₂层的临界频率f₀F₂的标准差约为059 关键词： COSMIC GPS/LEO掩星 电离层测高仪 电离层反演     

基于COSMIC掩星资料的全球第二对流层顶详细特征

使用2006年12月–2008年11月COSMIC (constellation observing system for meteorology, ionosphere and climate)掩星湿廓线资料对第二对流层顶的全球分布特征进行统计, 对比三个站点的无线电探空仪和COSMIC的对流层顶资料, 研究结果表明: 1) 第二对流层顶的出现频率在副热带急流区较高,冬季在北半球为50%–70%, 在南半球为20%–40%; 2) 赤道带的第二对流层顶出现频率约为20%–26%, 与越赤道急流和对流层顶上的毛卷云有关; 3) 在副热带急流区, 第一对流层顶的温度基本高于第二对流层顶; 4) 在热带, 对流层顶厚度和第二对流层顶出现频率随纬度减小; 热带以外, 对流层顶厚度随纬度增加, 在冬半球60^o有最大值7–8 km; 5) 单站点对流层顶的日变化剧烈程度与COSMIC和探空仪的对流层顶高度偏差正相关．     

非球对称电离层掩星数据反演

电离层掩星数据的传统反演方法是电离层球对称假设下的Abel变换反演方法,但是实际的电离层电子密度分布不是球对称的,电离层的非球对称分布给电离层电子密度反演带来误差.发展了一种新的非球对称电离层掩星反演方法,利用国际参考电离层模型提供的三维电离层电子密度分布先验信息来修正掩星总电子含量 ,再通过球对称假设下的Abel变换反演出电离层电子密度.利用新方法反演了星座气象、电离层和气候观察系统掩星实测数据,并将得到的反演结果与电离层探测器资料进行了比较.结果表明,新方法能够较好地反演出电离层电子密度. 关键词： 电离层掩星 电子密度 国际参考电离层模型     

Effect of spatial irregularities on the reconstruction of the ionospheric electron density profile on the basic of radio occultation observations

Based on the results of statistical analysis, an effective regularization algorithm for reconstructing the height profile of electron concentration was proposed, an algorithm that takes into account ionospheric irregularities and requires a minimum of a priori information: the values of Ne(0) and Ne(∞) and the positive definiteness of Ne ≥ 0.     

星-地无线电掩星技术探测火星大气和电离层

历史上几乎所有的行星探测任务都开展了无线电掩星实验,以探测行星的大气、电离层、行星环以及磁场,并取得了很多重要的科学成果.掩星发生时刻前后,测量航天器发出的信号穿过行星电离层和大气层时被遮掩而引起的信号频率、相位、幅度或极化等物理特性的变化,通过某种反演技术,可以得到大气的折射率廓线,推出中性大气的密度、温度、压强廓线以及电离层的电子浓度廓线.文章围绕中国“萤火1号”火星探测器（YH-1）火星探测计划中将要开展的星-地无线电掩星实验,介绍了该技术用于探测火星大气和电离层的相关情况.     

The determination of electron density profiles from refraction measurements obtained using holographic interferometry

The angles a fourth-harmonic holographic interferometer probing beam is refracted upon passing through a neodymium laser-produced plasma have been measured by varying the focus during reconstruction of the hologram. A method (not requiring the numerical inversion of an integral equation) for using such refraction measurements to give the plasma electron density profile is shown to produce a profile in agreement with that obtained from the phase information on the reconstructed in-focus interferogram.     

Characteristics of atmospheric gravity waves observed using the MU (Middle and Upper atmosphere) radar and GPS (Global Positioning System) radio occultation

The wind velocity and temperature profiles observed in the middle atmosphere (altitude: 10–100 km) show perturbations resulting from superposition of various atmospheric waves, including atmospheric gravity waves. Atmospheric gravity waves are known to play an important role in determining the general circulation in the middle atmosphere by dynamical stresses caused by gravity wave breaking. In this paper, we summarize the characteristics of atmospheric gravity waves observed using the middle and upper atmosphere (MU) radar in Japan, as well as novel satellite data obtained from global positioning system radio occultation (GPS RO) measurements. In particular, we focus on the behavior of gravity waves in the mesosphere (50–90 km), where considerable gravity wave attenuation occurs. We also report on the global distribution of gravity wave activity in the stratosphere (10–50 km), highlighting various excitation mechanisms such as orographic effects, convection in the tropics, meteorological disturbances, the subtropical jet and the polar night jet.     

GPS掩星一维弯曲角算子在四维变分资料同化系统中的实现方法研究

GPS无线电掩星资料的良好特性使其作为十分重要的观测资料在欧洲 及美国数值天气预报中效果明显. 本文设计了一维弯曲角算子在四维变分资料同化系统中的实现方法和质量控制策略. 详细阐述了一维弯曲角正演算子及其切线性/伴随算子在全球四维变分资料同化系统中的实现步骤和过程, 其中折射率计算中采用Rüeger的折射率最佳平均因子的三项表达式, 计算出更加精确的折射率值. 对2012年8月份的GPS无线电掩星资料进行了观测误差统计, 引入了更加符合四维变分资料同化系统实际情况的一维弯曲角观测误差模型和质量控制策略. 同时, 对比了观测误差统计试验中同化GPS无线电掩星资料的模式背景场和未同化GPS无线电掩星资料的背景场的观测误差统计结果, 发现同化GPS无线电掩星资料之后的观测误差统计结果在全球区域正作用十分明显, 尤其是在中低纬度地区, 高度在10 km 以上的区域观测误差减小十分明显. 关键词： GPS无线电掩星 一维弯曲角算子 四维变分同化系统 质量控制     

The minimum norm method for the determination of the charge density from elastic electron scattering data

Unphysical behavior in the QR algorithm based least squares determination of the expansion coefficients of the charge density obtained from limited information about the charge form factor occurs when the spread of the singular values in the matrix relating these quantities becomes too large. Setting the smallest singular values equal to zero in the singular value decomposition used in the minimum norm method yields a much more reasonable determination of the charge density. Increasing the size of the basis without increasing the range of the prior information about the charge form factor leads to ambiguities in the determination of the charge density. Numerical results in an analytic model are presented.     

The minimum norm method for the determination of the charge density from elastic electron scattering data

Unphysical behavior in the QR algorithm based least squares determination of the expansion coefficients of the charge density obtained from limited information about the charge form factor occurs when the spread of the singular values in the matrix relating these quantities becomes too large. Setting the smallest singular values equal to zero in the singular value decomposition used in the minimum norm method yields a much more reasonable determination of the charge density. Increasing the size of the basis without increasing the range of the prior information about the charge form factor leads to ambiguities in the determination of the charge density. Numerical results in an analytic model are presented.     

The determination of the nuclear ground state and transition charge density from measured electron scattering data

The evaluation of elastic and inelastic electron scattering cross sections is discussed in terms of the Fourier-Bessel expansion of the nuclear ground state and transition charge density, respectively. The method allows one to deduce the charge distributions and the moments as well as the corresponding errors, which originate on the one hand from the uncertainties in the measured data and on the other hand from the lack of knowledge about the large-q behaviour of the form factors; these two contributions are determined separately. The method is described and proved with an evaluation of pseudodata and then applied to ²⁰⁸Pb cross sections. For this nucleus, detailed results concerning the possible structure of the charge density are presented.     

On the compensation of chirp induced from semiconductor optical amplifier on RZ data using optical delay interferometer

The capability of an optical delay interferometer (ODI) to compensate the chirp induced on return-to-zero pulses amplified by a semiconductor optical amplifier (SOA) when operated under stressful conditions for its gain dynamics is investigated and demonstrated through extensive numerical simulation. The phase response of the ODI, which through its variation per time increment determines the chirp, is calculated at its crossed output port using an explicit expression. The theoretical analysis reveals that cascading the ODI after the SOA can reduce both the magnitude of the chirp and the variations of its peaks as well as those of the amplified pulses while ensuring error-free performance even for a tight combination of the critical parameters. In order for this goal to be successfully accomplished while not distorting the pulses acted on by the ODI the offset introduced by this passive element is computationally found that it must not exceed 10% of their repetition interval. Therefore the scheme can constitute a promising technological option for efficiently exploiting the chirp of an SOA and simultaneously using the SOA as gain block for direct amplification purposes.     

Application of maximum entropy method for the study of electron density distribution in SrS, BaS and PuS using powder X-ray data

A study of the electronic structure of the three sulphides, SrS, BaS and PuS has been carried out in this work, using the powder X-ray intensity data from JCPDS powder diffraction data base. The statistical approach, MEM (maximum entropy method) is used for the analysis of the data for the electron density distribution in these materials and an attempt has been made to understand the bonding between the metal atom and the sulphur atom. The mid-bond electron density is found to be maximum for PuS among these three sulphides, being 0.584 e/Å3 at 2.397 Å. SrS is found to have the lowest electron density at the mid-bond (0.003 e/ų) at 2.118 Å from the origin leaving it more ionic than the other two sulphides studied in this work. The two-dimensional electron density maps on (100) and (110) planes and the one-dimensional profiles along the bonding direction [111] are used for these analyses. The overall and individual Debye-Waller factors of atoms in these systems have also been studied and analyzed. The refinements of the observed X-ray data were carried out using standard softwares and also a routine written by the author     

An exact inversion method for the determination of spin–orbit potentials from scattering data

A generalized Newton–Sabatier inversion method which permits extraction from scattering data of central and spin-orbit potentials is presented. The inversion method originally developed by Sabatier and further elaborated by Hooshyar and Richardson, has been reformulated to lead to physically reasonable solutions and to allow for its numerical implementation. Numerical problems due to the occurrence of singularities in the transformation kernel are discussed and a successful application using schematic scattering data is reported. Received: 30 April 1997 / Revised version: 20 October 1997     

Symmetry properties of the electron density and following from it limits on the KS-DFT applications

ABSTRACT

At present, the Density Functional Theory (DFT) approach elaborated by Kohn with co-authors more than 50 years ago became the most widely used method for study molecules and solids. Using modern computation facilities, it can be applied to systems with million atoms. In the atmosphere of such great popularity, it is particularly important to know the limits of the applicability of DFT methods. In this report, I will discuss two cases when the conventional DFT approaches, using only electron density ρ and its gradients, cannot be applied (I will not consider the Ψ-versions of DFT). The first case is quite evident. In the degenerated states, the electron density may not be defined, since electronic and nuclear motions cannot be separated, the vibronic interaction mixed them. The second case is related to the spin of the state. As it was rigorously proved by group theoretical methods at the theorem level, the electron density does not depend on the total spin S of the arbitrary N-electron state. It means that the Kohn–Sham equations have the same form for states with different S. The critical survey of elaborated DFT procedures, taking into account spin, shows that they modified only exchange functionals, the correlation functionals do not correspond to the spin of the state. The point is that the conception of spin cannot be defined in the framework of the electron density formalism, which corresponds to the one-particle reduced density matrix. This is the main reason of the problems arising in the study by DFT of magnetic properties of the transition metals. The possible way of resolving these problems can be found in the two-particle reduced density matrix formulation of DFT.     

利用介质阻挡探针法测量大气压氦等离子体射流电子密度

分别利用电子的漂移速度和等离子体的传播速度计算了大气压下氦等离子体射流的电子密度。     

The trend of the APRGP velocity field and plates movement derived from GPS data

High-precision data processing theories and methods for the wide area GPS network–––Asia Pacific Regional Geodesy Project (APRGP), are systematically discussed in this article. With the software bernese5.0 update, the annual results of APRGP coordinate, velocity field and the trend of plate movement are reestimated, and the corresponding accuracy of adjustment with different constraints, also the velocity field of APRGP, are presented and analyzed. Conclusions could be drawn that Eurasian plate (EURA) rotates clockwise, the Australian plate (AUST) and the Indian plate (INDI) move from southwest to northeast, while the Pacific plate (PCFC) is drifting to northwest, which shows agreement with those of IGS results.     

利用等时退火法预估等温退火效应实验研究

对电离辐照损伤后的MOS器件的等温和等时退火特性进行了研究，结果发现，首先，100℃等 温退火是有效的，等时退火所需的全过程时间最短；其次，+5V栅偏压退火相对于0V和浮空 偏置条件，阈值电压恢复速度快、恢复程度大；最后，利用等时退火数据对等温效应进行了 理论预估，实验等温曲线和预估结果吻合得较好. 关键词： 等温退火 等时退火 MOS器件     

The vicinity of an equilibrium three-phase contact line using density-functional theory: density profiles normal to the fluid interface

The paper by Nold et al. [Phys. Fluids 26 (7), 072001 (2014)] examined density profiles and the micro-scale structure of an equilibrium three-phase (liquid–vapour–solid) contact line in the immediate vicinity of the wall using elements from the statistical mechanics of classical fluids, namely density-functional theory. The present research note, building on the above work, further contributes to our understanding of the nanoscale structure of a contact line by quantifying the strong dependence of the liquid–vapour density profile on the normal distance to the interface, when compared to the dependence on the vertical distance to the substrate. A recent study by Benet et al. [J. Phys. Chem. C 118 (38), 22079 (2014)] has shown that this could explain the emergence of a film-height-dependent surface tension close to the wall, with implications for the Frumkin–Derjaguin theory.     

Global features and trends of the tropopause derived from GPS/CHAMP RO data

The global characteristics and trends of the tropopause physical parameters,height and temperature,obtained from the GPS/CHAMP radio occultation(RO) data in the period from Jul.2001 to Oct.2008,were modeled and analyzed in this work.The global distribution and variation of these parameters with latitude were estimated and analyzed using the Empirical Orthogonal Function(EOF),which was introduced to reveal the possible relationship between the tropopause variations and global climate change.The tropopause he...