Contribution of new AAM data source to δLOD excitation

Data sets of the changes of the length of day (ΔLOD) measured by space geodetic techniques and of the atmospheric angular momentum (AAM) derived from global meteorological data by the National Meteorological Center (NMC) and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) are used to reanalyze and study the excitations of ΔLOD, and to examine and compare the contribution of each AAM series to ΔLOD. The main results are as follows. 1. The AAM reanalyzed with the assimilated global meteorological data by NCEP/NCAR are more accurate and have lower noise than the original AAM derived by NMC. The NCEP/NCAR-based AAM is more consistent with the changes of the length-of-day series. 2. The NCEP reanalysed AAM data may better explain the non-tidal LOD variations on intraseasonal to interannual time scales, especially on the quasi-biennial time scale. The atmosphere cannot, however, explain all LOD variations; other excitation sources are possible. 3. The effects of atmosphere on the estimated values of tides for ΔLOD components up to a month are weak. The preliminary results of the annual and semiannual tides can be estimated after removing the effects of atmosphere from ΔLOD. Received: 27 May 1998 / Accepted: 22 March 1999     

基于线路设计模型的一体化中线测设方法研究

本文针对线路（包括铁路和公路）的中线测设计算量大、野外作业条件的不可预知性和劳动强度大等特点,介绍了一种基于线路设计模型的一体化中线测设的教学模型及方法,以此为基础开发了实用的中线放样程序并运用于我国第一条磁悬浮线───交大青城磁浮列车试验示范城的中经测设中,实践证明一体化的思想及方法具有高效、灵活和可靠性等特点。     

地图数据库图形编辑软件（MDBGES）的设计与设想

图形编辑是ＧＩＳ中数据录入、更新及图形输出时的重要环节。本文阐述了地图数据库下图形编辑的原理、方法，ＭＤＢＧＥＳ的构成和功能，并分析了ＭＤＢＧＥＳ的试验结果，按照用户应用程序与ＤＢＭＳ的关系，提出了库函数的建立及其分类方案，以及一整套与地图数据库接口函数的原型。在用户与ＤＢＭＳ的接口规范化方面作了有益探索。此外，本文探讨了符号图形编辑的两种设想。     

微机窗口系统的一种实现方法

本文开发的弹出式窗口系统和下拉式菜单系统,具有显示速度快、通用性好、移植性强的特点。全部程序在VGA/EGA的PC机上调试通过,取得了较为满意的效果。笔者愿提供大家广为利用。     

美军数字化战场剖析及对我军测绘保障发展的几点认识

本文剖析了美军数字化部队和数字化战场的内涵，阐述了对发展我军测绘保障的一些认识。     

北京西山煤田滑脱构造的遥感研究

本文利用多种遥感资料提供的大量的新的构造信息,对北京西山煤田已有的地质认识和成果进行了重要补充和修改,划分出推覆型和滑型两种基本类型的滑脱构造,并详细研究了各个滑脱构造系统的影像特征、展布规律、几何形态、成因机制、演化历史以及控煤作用。     

密度计应用的一种新途径

通过理论计算以及实验分析证明,对颜色样品的密度测量可以转换为对其颜色外貌的计量,其计量结果与实际测量结果基本吻合,达到实用要求。     

空间灰度相关在影像纹理分类中的应用及分析

介绍了空间灰度相关法的11个纹理特征。试验表明,仅3个是描述性强的纹理特征。通过用t检验法来分类纹理,发现该方法具有良好的\     

A general formula and its inverse formula for gravimetric transformations by use of convolution and deconvolution techniques

A general formula is developed and presented for transformations among geoidal undulation, gravity anomaly, gravity disturbance and other gravimetric quantities. Using a spectral form of the general formula, a criterion has been built in order to classify these transformations into forward and inverse transformations in this paper. Then, the two-dimensional convolution techniques are applied to the general formula to deal with the forward transformation while the two-dimensional deconvolution techniques are employed to treat the inverse transformation and evaluate the inverse general formula. Concepts of convolution and deconvolution are also reviewed in this paper. The stability and edge effect problems related to the deconvolution techniques are investigated using simulated data and numerical tests are done to quantify the stability of the deconvolution techniques for estimated gravity information. Finally, the marine gravity information for the Norwegian-Greenland Sea area has been derived from ERS-1 altimetry data using the deconvolution techniques.     

遥感图像分类与后处理综合技术研究—基于约束满足神经网络方法

遥感图像计算机分类的精度问题是阻碍计算机遥感信息处理系统实用化的一个关键问题。将分类后处理中的分类结果平滑过程模型化为约束优化问题,采用神经网络方法把分类结果平滑过程与遥感图像分类过程结合起来,提出了基于约束满足神经网络的遥感信息分类与后处理综合技术。实验表明该方法可明显提高森林类型划分、土地利用调查等遥感应用专题的分类精度。