The geomagnetic solar flare effect identified by SIIG as an indicator of a solar flare observed by GOES satellites

This paper studies the efficiency of geomagnetic solar flare effects (gsfe) in X solar flare detection; so during the period 1999–2007 a comparison between solar flare (sf) observed by satellites of the Geostationary Operational Environmental Satellite (GOES) programme and gsfe published by the Service International des Indices Geomagnetiques (SIIG) is made.     

The beaming of external Compton emission

We consider a relativistically moving blob consisting of an isotropic electron distribution that Compton-scatters photons from an external isotropic radiation field. We compute the resulting beaming pattern, i.e. the distribution of the scattered photons, in the blob frame as well as in the observer’s frame by using the full Klein–Nishina cross section and the exact incident photon distribution. In the Thomson regime the comparison of our approach with Dermer (1995) results in concurrent characteristics but different absolute number of the scattered photons by a factor of f_corr = 3.09. Additionally, our calculation yields a slightly lower boost factor which varies the more from the corresponding value in Dermer (1995) the higher the spectral index p of the electron distribution gets.     

基于红外波段船载星光定向仪白昼恒星探测技术

摘要： 白昼恒星探测技术是船载星光定向仪海上应用的关键技术之一.本文基于实测星图给出白昼恒星探测技术的理论公式和实现方案.该技术针对实测红外星图中的背景噪声、伪星点、坏像素、对灰度背景的适应性问题,分别设计星图滤波算法、多帧伪星点剔除算法、坏像素索引表以及多梯度渐进积分时间调整算法.通过外场观星和组合导航实验验证该技术的有效性和精度.     

Evaluation of the IRI-2016 and NeQuick electron content specification by COSMIC GPS radio occultation,ground-based GPS and Jason-2 joint altimeter/GPS observations

We examined performance of two empirical profile-based ionospheric models, namely IRI-2016 and NeQuick-2, in electron content (EC) and total electron content (TEC) representation for different seasons and levels of solar activity. We derived and analyzed EC estimates in several representative altitudinal intervals for the ionosphere and the plasmasphere from the COSMIC GPS radio occultation, ground-based GPS and Jason-2 joint altimeter/GPS observations. It allows us to estimate a quantitative impact of the ionospheric electron density profiles formulation in several altitudinal intervals and to examine the source of the model-data discrepancies of the EC specification from the bottom-side ionosphere towards the GPS orbit altitudes. The most pronounced model-data differences were found at the low latitude region as related to the equatorial ionization anomaly appearance. Both the IRI-2016 and NeQuick-2 models tend to overestimate the daytime ionospheric EC and TEC at low latitudes during all seasons of low solar activity. On the contrary, during high solar activity the model results underestimated the EC/TEC observations at low latitudes. We found that both models underestimated the EC for the topside ionosphere and plasmasphere regions for all levels of solar activity. For low solar activity, the underestimated EC from the topside ionosphere and plasmasphere can compensate the overestimation of the ionospheric EC and, consequently, can slightly decrease the resulted model overestimation of the ground-based TEC. For high solar activity, the underestimated EC from the topside ionosphere and plasmasphere leads to a strengthening of the model underestimation of the ground-based TEC values. We demonstrated that the major source of the model-data discrepancies in the EC/TEC domain comes from the topside ionosphere/plasmasphere system.     

基体含量对复合材料结构稳定性的影响

基体含量影响着复合材料结构的性能,针对复合材料结构的稳定性设计,基于复合材料细观力学以及经典层合理论,分析复合材料层合板中的基体含量对于其材料性能,尤其是稳定性的影响.通过计算得出:随着基体含量的增加,材料的性能略有下降,但是由于基体含量增大而导致的单层板厚度增加,使得层合板的稳定性大幅提高.因此,在复合材料结构的稳定性设计中,应该考虑基体含量的影响.     

Superclustering of galaxies and X-ray sources

An attempt is made to compare optical properties of Abell clusters with X-ray sources.     

Hi content in cluster and supercluster galaxies

In this lecture I review part of the published and unpublished observational evidence showing that cluster spiral galaxies are hydrogen deficient. Always using observational data, it is argued that the deficiency is due to the interaction between the galaxies and the intergalactic medium. Furthermore it is shown that the stellar population of deficient galaxies has also been affected and a brief discussion is given of the mechanisms at work.     

Galactic Evolution of the Light Elements: A New Set of B Observations

The boron 2500 spectral region has been observed with the Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) in a new set of metal-poor stars and analyzed by spectrum synthesis technique, adopting the most recent model atmospheres. By taking into account the Li and Be abundances available from the literature for this same set of objects, the resulting patterns of their light elements abundances cannot be easily justified with the currently known stellar structure scenarios. The finding of real differences in the B content between stars with very similar stellar characteristics suggest that also production effects, rather than depletion and/or mixing only, should be taken into account as a possible and valuable explanation.     

Self-similar solutions to stellar winds with cosmic rays

A two-fluid model is used to study the time evolution of stellar winds including the dynamical effect of cosmic rays. Neglecting the diffusion of cosmic rays, we seek self-similar solutions to spherically symmetric winds with a termination shock. The velocity upstream of the shock is taken to be zero. Physical solutions are those that can connect the shock to the star with the velocity approaching zero at the star. Two parameters govern the behaviour of the solutions, namely, the ratio of the upstream sound speed to the shock speed (in an inertial frame) and the gravitation potential of the central star. In some parameter regimes, no physical solution is possible.     

铝-锂合金的真空熔炼

 在ZG-25型中频感应真空炉中进行了铝-锂合金的熔炼与铸锭。真空度为66Pa。考察了普通石墨坩埚、氧化铝坩埚,以及氧化锌涂料、氮化硼涂料与铝-锂熔体的反应。抄到了在真空下控制铝-锂熔体中锂含量的方法。在不使用钛-硼细化剂的条件下,铸锭呈细小等轴晶组织,其成分均匀,夹杂物极少。真空熔炼可使合金中的氢、钾,钠等杂质含量显著地降低。