New confirmation of image-processing techniques for astrometry of Saturn and its satellites     

Q. Y. Peng 《Monthly notices of the Royal Astronomical Society》2005,359(4):1597-1600

The image-processing techniques used by Peng et al. are further improved to measure precisely the positions of Saturn and its satellites. 495 CCD images taken with the 1-m telescope at the Yunnan Observatory during the years 2002–2004 are processed with these techniques. These measured pixel positions are compared to their theoretical positions computed with the ephemerides of TASS1.7 for the satellites and JPL DE405 for Saturn itself. Analysis of the data for the intersatellite positions among four bright Saturnian satellites (S3–S6) and for Saturn–satellite (i.e. Saturn–Titan) positions shows that these measured positions have the same dispersions, i.e. about 0.05 and 0.06 arcsec in right ascension and declination, respectively. However, for the fainter satellites, Enceladus and Mimas, poorer residuals up to 0.1 and 0.2 arcsec, respectively, in both directions are found mainly due to their small separations from the primary planet and short exposure time in order to obtain useful images of Saturn.  相似文献   

Effect of soil interaction on the performance of liquid column dampers for seismic applications     

Aparna Ghosh  Biswajit Basu 《地震工程与结构动力学》2005,34(11):1375-1389

The effects of soil–structure interaction (SSI) while designing the liquid column damper (LCD) for seismic vibration control of structures have been presented in this study. The formulation for the input–output relation of a flexible‐base structure with attached LCD has been presented. The superstructure has been modelled by a single‐degree‐of‐freedom (SDOF) system. The non‐linearity in the orifice damping of the LCD has been replaced by equivalent linear viscous damping by using equivalent linearization technique. The force–deformation relationships and damping characteristics of the foundation have been described by complex valued impedance functions. Through a numerical stochastic study in the frequency domain, the various aspects of SSI on the functioning of the LCD have been illustrated. A simpler approach for studying the LCD performance considering SSI, using an equivalent SDOF model for the soil–structure system available in literature by Wolf (Dynamic Soil–Structure Interaction. International Series in Civil Engineering and Engineering Mechanics. Prentice‐Hall: Englewood Cliffs, NJ, 1985) has also been presented. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

极限波浪运动特性的非线性数值模拟   总被引：1，自引：0，他引：1       下载免费PDF全文

宁德志  滕斌  姜立明  臧军 《海洋学报》2008,30(3):126-132

利用时域高阶边界元方法建立了模拟极限波浪运动的完全非线性数值模型,其中自由水面满足完全非线性自由水面条件.采用半混合欧拉-拉格朗日方法追踪流体瞬时水面,运用四阶Runge-Kutta方法更新下一时间步的波面和速度势,同时应用镜像格林函数消除水槽两个侧面和底面上的积分.研究中利用波浪聚焦的方法产生极限波浪,并且在水槽中开展了物理模型实验,将测点试验数据与数值结果进行了对比,两者吻合得很好.对极限波浪运动的非线性和流域内速度分布进行了研究.  相似文献   

遥感影像融合方法的精度评价     

许辉熙 《测绘与空间地理信息》2009,32(6):11-14

目前,高分辨率全色遥感影像和低空间分辨率的多光谱遥感影像融合是影像融合技术应用的主流.EN-VI 4.4遥感影像处理软件影像融合处理的工具--SPEAR提供了PCA变换、Gram-Schmid变换、Brovey变换和HSV变换4种专门用于全色与多光谱遥感影像融合的算法.以ETM+全色与多光谱遥感影像融合为例,选择熵、偏差和相关系数3个定量指标,对采用4种融合方法得到的影像进行评价.经综合评价和比较,实验的4种影像融合算法中,Gram-Schmidt变换效果最好.  相似文献   

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周硕愚  吴云  施顺英  姚运生 《大地测量与地球动力学》2007,27(4):92-99

??????????????????????????о????40????????????????????α估GPS????????????????????????????????????????????????????????????????????????????????????????￡????????????????????????????????????????????????????????????????????????????????????????????????????????????顢???塢???????????,????????????????????????????????????????????????????1??????????????????????????????????????????????????????????????????????鵽????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????SOC??????????????????????????????????????????????????????????????????????е?????????  相似文献   

一种基于点特征的高精度图像配准方法     

范大昭  任玉川  贾博  张红敏  王鹏 《地理信息世界》2007,5(5):66-70

提出了一种基于点特征的多源图像高精度配准方法。通过在遥感影像上提取密集特征点,利用多种方法结合进行严格匹配获得同名点对。通过构建不规则三角网分割影像,再利用仿射变换模型实现每个三角形的配准。实验证明了该方法的有效性和较高的适用性。  相似文献   

高挂山—牛头寨地区小型环形影象构造分析及其找矿意义     

钱惠林 《湖南地质》1989,8(2):18-22

高挂山—牛头寨地区,通过大比例尺航片解译,发现6个大小不等的小型环形影象信息。这些环形影象与岩浆活动、已知矿床、矿化点、重砂异常、物化探异常等的分布有着内在的联系。为预测找矿远景区和找隐伏矿床提供了影象依据。  相似文献   

Single-station decomposition of seismograms for subevent time histories     

Massimo Di  Bona John Boatwright 《Geophysical Journal International》1991,105(1):103-117

  相似文献   

贺兰山群变质杂岩中的变余动力变质岩     

胡能高  杨家喜  王涛 《地球科学与环境学报》1993,(4)

贺兰山群变质杂岩形成于晚太古代,遭受过多期变质和变形的改造,其中发育了不同期次和层次的动力变质岩。变余韧性剪切带内发育了条带状片麻岩和变粒岩,相伴有变余鞘褶皱和构造透镜体,变余韧性剪切带的变形发生在较低的温度、压力条件下,地壳加厚作用的初期。变余糜棱岩貌似条带状片麻岩,但在青石中保留了早期石英拔丝构造和加粗的动态重结晶长石集合体。糜棱岩化作用的温度在550℃以上,变形后沿面理形成了饼状或椭圆状青石,变晶时温度近600℃,压力近300MPa。  相似文献   

APPLICATIONS OF ARTIFICIAL INTELLIGENCE TECHNIQUES TO REMOTE SENSING*     

John E. Estes  Charlene Sailer  Larry R. Tinney 《The Professional geographer》1986,38(2):133-141

Remote sensing is a geographic analysis tool capable of producing large quantities of data in the spectral, temporal and spatial domains. Techniques for automating the image analysis process would be advanced by the inclusion of artificial intelligence techniques in the design of image processing systems. The remote sensing application which show promise for successful implementation of artificial intelligence techniques are intelligent onboard processing, advanced database interrogation, and the automated analysis of multispectral imagery.  相似文献