Nighttime thermospheric meridional neutral winds inferred from ionospheric h′F and hpF2 data

Nighttime thermospheric meridional winds aligned to the magnetic meridian have been inferred using h′F and hpF2 ionosonde data taken from two equatorial stations, Manaus (2.9°S, 60.0°W, dip latitude 6.0°N) and Palmas (10.17°S, 48.2°W, dip latitude 6.2°S), and one low-latitude station, Sao Jose dos Campos (23.21°S, 45.86°W, dip latitude 17.26°S), during geomagnetic quiet days of August and September, 2002. Using an extension of the ionospheric servo model and a simple formulation of the diffusive vertical drift velocity, the magnetic meridional component of the thermospheric neutral winds is inferred, respectively, at the peak (hpF2) and at the base (h′F) heights of the F region over Sao Jose dos Campos. An approach has been included in the models to derive the effects of the electrodynamic drift over Sao Jose dos Campos from the time derivative of hpF2 and h′F observed at the equatorial stations. The magnetic meridional winds inferred from the two methods, for the months of August and September, are compared with winds calculated using the HWM-90 model and with measurements from Fabry–Perot technique. The results show varying agreements and disagreements. Meridional winds calculated from hpF2 ionospheric data (servo model) may produce errors of about 59 m/s, whereas the method calculated from the F-region base height (h′F) ionospheric data gives errors of about 69 m/s during the occurrence of equatorial spread-F.     

Mars Express/ASPERA-3/NPI and IMAGE/LENA observations of energetic neutral atoms in Earth and Mars orbit

The low energy neutral atom imagers on Mars Express and IMAGE have revealed that the neutral atom populations in interplanetary space come from a variety of sources and challenge our current understanding of heliospheric physics. For example, both in cruise phase and at Mars, the neutral particle instrument NPD on Mars Express observed “unexplained neutral beams” unrelated to Mars which appear to be either of heliospheric or solar wind origin. Likewise, the NPI instrument on Mars Express has revealed streams of neutral atoms with different properties than those observed by NPD. Independently, IMAGE/LENA has reported neutral atom observations that may be interpreted as a “secondary stream” having different characteristics and flowing from a higher ecliptic longitude than the nominal upstream direction. Both sets of observations do not appear to fit in easily with the neutral atom environment from 1.0 to 1.57 AU as it is currently understood. In this paper, we examine some highly suggestive similarities in the IMAGE/LENA and Mars Express/ASPERA-3/NPI data to try to determine potential origins for the observed signal.     

Monte Carlo calibration of the response of the University of Chicago’s Cosmic Ray Nuclei Experiment (CRNE) on IMP-8 to electrons above 0.5 MeV

Modern instrument-simulation techniques offer the possibility of increasing the scientific yield from archival space datasets. In this paper, we report on a simulation of the electron response of the University of Chicago’s Cosmic Ray Nuclei Experiment (CRNE) instrument on the IMP-8 satellite. IMP-8/CRNE returned data from 1973 to 2006. The CRNE particle telescope was designed to measure the isotopic composition of Galactic cosmic-ray (GCR) nuclei and has also been used in many studies of protons and ions above 10 MeV/nucleon from solar energetic particle (SEP) events. But CRNE also functions as a highly-capable detector for solar electrons above 0.5 MeV, an energy range that has not been extensively studied. Utilization of the CRNE electron data has heretofore been limited by the fact that CRNE was never calibrated for electrons. We have therefore used the GEANT4 Monte Carlo simulation package to model the CRNE response to electrons and (separately) protons for multiple energies and incident angles. The results were used to compute the energy- and angle-dependence of the effective area and the energy-dependence of the geometric factor. The response to protons, which was already well understood, was used to verify the mass model, the simulation settings, and the post-processing software. Our simulation of the IMP-8/CRNE electron response now allows analysis of hundreds of relativistic solar electron events observed by CRNE over the years, including studies of evolution of electron energy spectra with high time resolution. We show examples of these results and briefly discuss potential applications to future scientific investigations.     

Forbush decreases and solar events seen in the 10–20 GeV energy range by the Karlsruhe Muon Telescope

Since 1993, a muon telescope located at Forschungszentrum Karlsruhe (Karlsruhe Muon Telescope) has been recording the flux of single muons mostly originating from primary cosmic-ray protons with dominant energies in the 10–20 GeV range. The data are used to investigate the influence of solar effects on the flux of cosmic rays measured at Earth. Non-periodic events like Forbush decreases and ground level enhancements are detected in the registered muon flux. A selection of recent events will be presented and compared to data from the Jungfraujoch neutron monitor. The data of the Karlsruhe Muon Telescope help to extend the knowledge about Forbush decreases and ground level enhancements to energies beyond the neutron monitor regime.     

波音757右IDG电源输出中线接地点故障分析

以实际维修工作中遇到的波音757右整体驱动发电机（IDG）电源输出中线接地点故障为例．对该故障的现象、特点和难点进行分析和判断,找到了故障的原因,并提出了排故方案和维修建议。     

Nb基合金中氧原子扩散及团簇化的第一性原理

利用第一性原理计算,研究了氧原子在Nb中的扩散现象以及施加应变的影响,并对氧原子在Nb-Ti、Nb-Zr合金中的团簇化进行了计算分析。发现在单向应变下,在平行于应变方向上,氧原子的扩散势垒随着应变的增大不断减小,当应变为10%时,扩散激活能从初始的0.92eV降低至0.5eV左右;在垂直于应变方向上,氧原子更容易扩散至被拉长的八面体间隙中,即单向应变下氧原子会在Nb中沿应变方向聚集排列,这会在实际材料中导致应力的集中。计算研究了氧原子在Nb合金中的团簇化问题,发现在纯Nb中,氧原子倾向于均匀分布而不是形成氧原子对;添加合金元素Ti和Zr后,随着氧原子浓度的升高,氧原子对将在合金元素周围形成,Zr周围氧原子对的形成可使体系的能量降低0.29eV。     

高能固体推进剂技术回顾与展望

综合了国内外高能固体推进剂及其含能原材料研究历史和现状，分析了高能推进剂的最新进展和未来发展趋势，提出并简要讨论了固体推进剂高能化相关的若干问题。     

国外固体推进剂技术现状和发展趋势

总结了固体推进剂技术发展情况，综述了国外固体推进剂技术现状，重点介绍了国外高能量密度材料、含能粘合剂及增塑性，氧化剂，添加剂以及新型固体推进情况，并提出了固体推进剂技术今后的发展趋势。     

Energetic particle signatures of geoeffective coronal mass ejections

We have studied statistically associations of moderate and intense geomagnetic storms with coronal mass ejections (CMEs) and energetic particle events. The goal was to identify specific energetic particle signatures, which could be used to improve the predictions of the geoeffectiveness of full and partial halo CMEs. Protons in the range 1–110 MeV from the ERNE experiment onboard SOHO are used in the analysis. The study covers the time period from August 1996 to July 2000. We demonstrate the feasibility of energetic particle observations as an additional source of information in evaluating the geoeffectiveness of full and partial halo CMEs. Based on the observed onset times of solar energetic particle (SEP) events and energetic storm particle (ESP) events, we derive a proxy for the transit times of shocks driven by the interplanetary counterparts of coronal mass ejections from the Sun to the Earth. For a limited number of geomagnetic storms which can be associated to both SEP and ESP signatures, we found that this transit time correlates with the strength of geomagnetic storms.     

冷原子干涉仪发展现状与应用分析

基于冷原子干涉仪的量子传感器具有极高的理论精度,在自然科学的各个领域特别是重力测量和惯性传感领域有着广泛的应用。首先介绍了原子干涉仪的基本原理,在此基础上给出了基于双光子受激Raman跃迁的脉冲式Mach-Zehnder原子干涉仪的干涉相位,描述了原子干涉仪在重力仪和陀螺上的应用及其发展历程,着重分析了当前发展最成熟的原子重力仪的发展历程和趋势,指出了原子干涉仪应用的发展方向。