GPS data processing of networks with mixed single- and dual-frequency receivers for deformation monitoring

In order to obtain crustal deformations of higher spatial resolution, existing GPS networks must be densified. This densification can be carried out using single-frequency receivers at moderate costs. However, ionospheric delay handling is required in the data processing. We adapt the Satellite-specific Epoch-differenced Ionospheric Delay model (SEID) for GPS networks with mixed single- and dual-frequency receivers. The SEID model is modified to utilize the observations from the three nearest dual-frequency reference stations in order to avoid contaminations from more remote stations. As data of only three stations are used, an efficient missing data constructing approach with polynomial fitting is implemented to minimize data losses. Data from large scale reference networks extended with single-frequency receivers can now be processed, based on the adapted SEID model. A new data processing scheme is developed in order to make use of existing GPS data processing software packages without any modifications. This processing scheme is evaluated using a sub-network of the German SAPOS network. The results verify that the new scheme provides an efficient way to densify existing GPS networks with single-frequency receivers.     

基于现实飞行条件下的飞行员英语陆空通话教学研究

本文首先提出目前飞行员英语陆空通话课堂教学中存在的问题和不足，在此基础上，结合具体事例说明了实际通话中飞行员用语失误或误解所造成的飞行事故，强调了实际飞行条件下飞行员英语陆空通话综合能力提高的必要性和迫切性。最后分析并提出了飞行员英语陆空通话课堂教学方法改进的新举措。     

单框架控制力矩陀螺复合操纵律设计

为改善单框架控制力矩陀螺(SGCMG)动态操纵律的奇异回避和逃逸性能,文章设计了一种基于前馈和反馈的复合操纵律.当SGCMG系统远离奇异时,不引入前馈,仅采用基于反馈的动态操纵律;当SGCMG系统接近或陷入奇异时,在动态操纵律的基础上,引入前馈信息,辅助SGCMG系统回避或逃逸奇异.复合操纵律不但可以保留动态操纵律的优点,不需计算Jacobi矩阵的伪逆,计算简单,易于实现,而且可以逃逸椭圆型内部奇点.对某SGCMG系统的仿真结果表明,复合操纵律是可行的.     

普通高校英语专业学生增强第二外语显性优势研究

对提高英语专业学生的就业竞争力而言,强势的第二外语是一个显性优势。通过观念更新,整合校内外资源,在具体的教学中对学生加以引导和教育,使得英语专业学生具备第二外语优势,增强就业竞争力。     

VPAC——碳纤维结构件制孔和安装环槽钉的自动化解决方案

垂尾的预装要求在碳纤维增强塑料(CFRP)的生产过程中具有相适应的定位能力以克服公差累积。对于以手工方式满足产品质量要求和生产成本目标,就劳动时间而言,技能和资源的配置就具有重要意义。保证工作环境的安全是采用自动化的另一个原因,这减少了工人对加工过程产生的CFRP尘埃的接触。为了达到用户对安全、质量和经济方面的要求,德国宝捷公司向用户推荐并生产了一种非常先进的紧固机器,所给出的自动化解决方案满足了当前的需求以及其他尚待公布的项目和未来的产品。     

The hemispheric asynchrony of polar faculae during solar cycles 19–22

We investigate the north–south (N–S) asynchrony of the polar faculae and compare it with the hemispheric asynchrony of solar activity at low latitudes. We find that, (1) both the solar activity at high and low latitudes do not synchronously occur in the northern and southern hemispheres, there is phase shifts between the two hemispheres; (2) the N–S asynchrony of the polar faculae is a function of latitudes, implying that the asynchrony of the polar faculae between the two hemispheres is related to the hemispheric asymmetry and latitudinal distribution of the polar faculae.     

Medium-scale traveling ionospheric disturbances (MSTID) modeling using a dense German GPS network

The MSTIDs are wave-like perturbations of the ionospheric plasma, which cause the most common ionospheric disturbances in mid-latitude regions. Generally the MSTIDs have velocities of several hundred meters per second and wavelengths of several hundred kilometers. The wave-like effect of the MSTID is one of the main obstacles for accurate interpolation of ionospheric corrections in a medium-scale reference GPS network. In this paper we show a new method of detecting and modeling MSTIDs using dense German GPS network. The between-epoch single difference ionospheric delays from a medium scale dense GPS network are used to estimate the parameter of the MSTID e.g. amplitude, wavelength and velocity. The efficiency of the approach is tested with data from about 320 GPS stations in and near Germany. A MSTID wave moving from east to west across Germany was observed at September 27 in 2009. Its wavelength is about 302 km, with a period of ∼7 min and velocity of about 700 m/s.     

A coupled finite-element state-space approach for synchronousgenerators. I. model development

Presented here is the development of a time stepping coupled finite-element state-space (CFE-SS) modeling environment, totally within the natural time domain ABC flux-linkage frame of reference, to predict the steady-state machine parameters and performance characteristics, including laminated iron core losses, of salient-pole synchronous machines. The time stepping CFE-SS model allows one to rigorously account for the full synergistic impact of space harmonics and time harmonics on the machine parameters and performance characteristics     

高屏蔽、低损耗、低驻波电缆组件的研制

简述了高屏蔽射频同轴电缆组件的设计要点，并介绍了国外超高屏蔽射频电缆的结构和性能，较详细地讨论了自行研制的电缆组件的主要技术指标、电压驻波比、插入损耗、射频泄漏及电缆屏蔽衰减等测试方法并给出了测试结果。在２～１８ＧＨｚ频带范围内：ＶＳＷＲ≤１．４；插入损耗为２ｄＢ；在２ＧＨｚ：射频泄漏不大于－９０ｄＢ，屏蔽衰减为９０ｄＢ．达到了预定的技术指标。