A Keystone Transform Without Interpolation for SAR Ground Moving-Target Imaging

Synthetic aperture radar (SAR) image formation for a ground moving target necessitates the compensation of the unknown target trajectory. The keystone transform has been employed to remove the linear component of the range migration for the moving target, where interpolation is required. In this letter, a realization of the keystone transform avoiding interpolation is presented. The kernel of this transform, i.e., the range-frequency-dependent azimuth time rescaling, is implemented using only complex multiplications and fast Fourier transforms based on the scaling principle, which has been successfully applied in the equalization of the space-variant range cell migration in SAR processing. In addition, the moving target is coarsely focused according to the SAR geometry and the platform velocity while exploiting the scaling principle. This preliminary focusing is helpful in the isolation of the moving target from ground clutter, so as to facilitate a more refined processing with respect to each mover. SAR raw data combined with simulated echoes of moving targets are utilized to validate the presented approach     

High-Resolution Forecast Models of Water Vapor Over Mountains: Comparison With MERIS and Meteosat Data

Propagation delay due to variable tropospheric water vapor (WV) is one of the most intractable problems for radar interferometry, particularly over mountains. The WV field can be simulated by an atmospheric model, and the difference between the two fields is used to correct the radar interferogram. Here, we report our use of the U.K. Met Office Unified Model in a nested mode to produce high-resolution forecast fields for the 3-km-high Mount Etna volcano. The simulated precipitable-water field is validated against that retrieved from the Medium-Resolution Imaging Spectrometer (MERIS) radiometer on the Envisat satellite, which has a resolution of 300 m. Two case studies, one from winter (November 24, 2004) and one from summer (June 25, 2005), show that the mismatch between the model and the MERIS fields ( rms = 1.1 and 1.6 mm, respectively) is small. One of the main potential sources of error in the models is the timing of the WV field simulation. We show that long-wavelength upper tropospheric troughs of low WV could be identified in both the model output and Meteosat WV imagery for the November 24, 2004 case and used to choose the best time of model output.     

脉冲激光抽运铷原子钟研究

对脉冲激光抽运、微波分立场共振和自由感应微波辐射或者光吸收检测方案（POP）的铷原子钟进行了理论和实验研究。理论研究表明,POP原子钟,可以消除光频移,有效地减小腔牵引频移,从而有利于提高原子钟的稳定度;且微波脉冲面积为π/2时,微波Ramsey条纹的线宽为传统Ramsey条纹的一半,从而提高了原子品质因数。实验获得了...     

Modest Maps的Flash网络地图发布与应用

本文分析了Adobe Flash技术在网络地图发布前端技术上的优势和应用现状,选择开源Flash地图组件Modest Maps作为开发工具,在其上添加了一些组件模块,以"5.12地震信息显示"为示例,实现了基于Modest Maps的Falsh网络地图发布和简单的空间分析.     

Self-calibration Applied in Converting Simulation Surveying

In the field of converting simulation surveying and traditional close range photogrammetry, it has been developed so far to survey objects by commercial digital camera and this technique is applied widely in every part of production. In order to get three-dimensional information of objects, commercial digital camera must be examined. For a long time, digital camera has been examined by DLT. Then there must be a high-precision control field. For realizing surveying without control points, a method for self-calibration is proposed.     

Observation on height changes of chinese tide gauges by GPS

IntroductionBecause of global temperature rising and glacierthawing,the sea level has risen about 10-25 cmin the past century[1]. The sea level change isone of the main ai ms in global change monito-ring. Presently the basic tool used in sea levelmonitori…     

Photogrammetry Education for Multidisciplinary Geomatics in China

IntroductionThe word photogrammetry comes from Greekwords photos ( meaning “light”) , gramma( meaning that which is drawn or written) andmetron ( meaning“to measure”) . It originallysignifies measuring graphically by means oflight[1].The development o…     

周期基数插值对偶尺度函数和对偶小波

在对二维周期基数插值小波的尺度函数和小波函数研究的基础上,对二维周期基数插值小波的对偶尺度函数和对偶小波进行了研究,得到了一系列重要的结论。     

横向受荷桩的最轻重量设计

尝试建立变截面桩的挠曲线微分方程,继而提出了变截面优化桩的概念,并给出了端承桩的一种优化算法。还以圆截面大孔径挖孔灌注桩为例,在桩顶受竖向荷载、水平横向力及弯矩作用时,进行了最轻重量设计。通过计算表明,使用变截面优化桩可使桩的体积减少30%以上。