GPS-only gravity field recovery with GOCE,CHAMP, and GRACE

Gravity missions such as the Gravity field and steady-state Ocean Circulation Explorer (GOCE) are equipped with onboard Global Positioning System (GPS) receivers for precise orbit determination (POD), instrument time-tagging, and the extraction of the long wavelength part of the Earth’s gravity field. The very low orbital altitude of the GOCE satellite and the availability of dense 1 s GPS tracking data are ideal characteristics to exploit the contribution of GPS high-low Satellite-to-Satellite Tracking (hl-SST) to gravity field determination. We present gravity field solutions based on about 8 months of GOCE GPS hl-SST data from 2009 and compare the results with those obtained from the CHAllenging Minisatellite Payload (CHAMP) and Gravity Recovery And Climate Experiment (GRACE) missions. The very low orbital altitude of GOCE significantly improves gravity field recovery from GPS hl-SST data above degree 20, but not for the degrees below 20, where the quality of the spherical harmonic coefficients remains essentially unchanged. Despite the limited time span of GOCE data used, the gravity field of the Earth can be resolved up to about degree 115 using GPS data only. Empirically determined phase center variations (PCVs) of the GOCE onboard GPS helix antenna are, however, mandatory to achieve this performance.     

无人机前开伞式降落过程动力学建模与仿真

文章分析了某型无人机降落伞回收阶段的动力学过程,对各工作阶段的无人机和降落伞的组合体进行了数学建模,使用Matlab软件中的Simulink组件搭建了无人机伞降过程的仿真模型,按照真实飞行和回收工况进行了计算,通过仿真结果与试验数据的比较,验证了模型的正确性.     

大型贮箱结构及工艺性研究

通过分析贮箱的类型及特点,研究贮箱放置布局,并以土星V为例研究分析了大型贮箱结构特点和制造的工艺性,提出了大型贮箱结构方案和制造工艺的发展方向。     

用于PSK载波提取的改进型逆调制环的研究

文章介绍了一种在全数字接收机中可用软件方式实现的MPSK载波提取方法———改进型逆调制环,并给出了性能分析。该方法适用于高速且速率可变的PSK调制技术,能较好地消除悬搁现象,适合于用DSP或FPGA来实现。     

圆顶相控阵的初步设计

文章介络了圆顶阵的概念、实现宽角扫描的原理;利用几何光学法分析了圆弧阵的口径场幅度、固定移相器的相移;同时,给出了圆顶单元的几种设计方法。最后,对文中推导出的重要公式进行了验证,并从中找到适合工程实现的设计参数：结果表明,几何光学法是分析圆顶相控阵极其有效的方法,圆波导是圆顶单元比较好的选择,圆顶相控阵在实现宽角扫描方面具有成熟的理论依据。     

网络环境下的英语教学模式初探

网络化英语教学解决了英语教学中有限传授和无限需求、特定的教学与广泛需求、知识信息的有限实效与快速更新的矛盾。网络英语教学的模式主要包括网络个别化英语教学模式、讲授或网络教学模式。网络英语教学中的学习模式包括网上讨论学习模式，互动式学习模式等。以计算机教学为主要手段的教学的开展，为推进英语教学带来了许多启发，教师只有具备了现代化教育理论才能适应未来教育的发展变化。     

我国品牌战略存在的问题与对策

总体上我国仍是品牌弱国,品牌意识不强、知名品牌不多、品牌带动作用不大、品牌的技术创新力度不够、品牌培育的市场环境不好等问题普遍存在.加强品牌战略研究,积极营造良好的社会环境,进一步提高技术创新能力,发挥企业在推进品牌战略中的主体作用将是今后我国推进品牌战略的重要措施.     

基于Authorware技术的EDS课件开发

介绍了用Authorware6.0开发研制飞机EDS系统课件的设计步骤，方法及具体实现过程，并对该课件的特点进行了介绍。     

语音识别技术应用于航空控制系统

介绍了语音识别技术基本原理及在航空控制领域的应用。     

THE APPLICATION OF SATELLITE POSITIONING TECHNOLOGY AND ITS INDUSTRIALIZATION IN CHINA

Satellite positioning technology has been widely used in all kinds of military and civil land, marine, space and aeronautical target positioning tasks, naviga tion activities and accurate surveying measurements since 90 s in the last cen tury due to its advantage in providing all-weather, real-time, three dimensional and high precision positioning information, as well as speed and accurate timing information. By now, it has already formed a new hi-tech industry basically.This paper briefly reviews the development of the global satellite positioning and navigation technologies including the basic information of China's "Plough navigation system", introduces the history of satellite positioning technology and its major application fields as well as the status quo of this being industri alized trade in China, gives an account of the writers' vision for the application and prospect of the satellite positioning technologies in China, and approaches the tactics and stresses of the satellite positioning technology's application and its industrialization future in China.