单频GPS整周模糊度动态快速求解的研究   总被引：2，自引：1，他引：2  

刘立龙  刘基余  李光成 《武汉大学学报(信息科学版)》2005,30(10):885-887

提出了一种动态快速求解整周模糊度的方法,即先对系数阵进行QR分解,然后通过矩阵变换使模糊度参数和位置参数分离,从而降低矩阵的维数,满足实时动态求解的要求,最后应用LAMBDA方法搜索模糊度。为验证该算法,用单频GPS接收机进行了静态定位和动态定位两种试验。结果表明,静态定位误差小于1cm,动态定位误差小于3cm。由此可见,该方法能够为动态用户快速而精确地实施GPS单频动态定位。  相似文献   

冬季浙闽沿岸水分布的短期变动与风的关系初探   总被引：6，自引：0，他引：6  

张彩云  商少凌  陈德文  商少平 《遥感学报》2005,9(4):452-458

利用1999年7月至2003年5月期间的遥感数据,包括AVHRR海表层温度、QuikSCAT风场和风应力数据,在分析4年内月平均遥感温度场和风场特征与历年现场观测所获得的认识一致的基础上,选取2002年002-008天这一连续晴空的时段,尝试建立简单的沿岸冷水影响面积表征方法,初步探讨了冬季台湾海峡浙闽沿岸水分布的短期变动与风应力之间的关系。结果表明,风是决定冬季台湾海峡海表层温度逐日变动的关键因素,日平均SST与风应力的相关系数R2达到0·90。采用温度法(SST≤17℃)和温度空间距平法(≤-1℃)表征的浙闽沿岸水影响面积的变化趋势基本一致,而且影响面积的逐日变动与风应力显著相关,二者的相关系数R2分别达到0·90和0·91。  相似文献   

Integer aperture bootstrapping: a new GNSS ambiguity estimator with controllable fail-rate   总被引：1，自引：0，他引：1  

P.J.G. Teunissen 《Journal of Geodesy》2005,79(6-7):389-397

In this contribution, we introduce a new bootstrap-based method for Global Navigation Satellite System (GNSS) carrier-phase ambiguity resolution. Integer bootstrapping is known to be one of the simplest methods for integer ambiguity estimation with close-to-optimal performance. Its outcome is easy to compute due to the absence of an integer search, and its performance is close to optimal if the decorrelating Z-transformation of the LAMBDA method is used. Moreover, the bootstrapped estimator is presently the only integer estimator for which an exact and easy-to-compute expression of its fail-rate can be given. A possible disadvantage is, however, that the user has only a limited control over the fail-rate. Once the underlying mathematical model is given, the user has no freedom left in changing the value of the fail-rate. Here, we present an ambiguity estimator for which the user is given additional freedom. For this purpose, use is made of the class of integer aperture estimators as introduced in Teunissen (2003). This class is larger than the class of integer estimators. Integer aperture estimators are of a hybrid nature and can have integer outcomes as well as non-integer outcomes. The new estimator is referred to as integer aperture bootstrapping. This new estimator has all the advantages known from integer bootstrapping with the additional advantage that its fail-rate can be controlled by the user. This is made possible by giving the user the freedom over the aperture of the pull-in region. We also give an exact and easy-to-compute expression for its controllable fail-rate.  相似文献   

笛卡儿坐标系的双多普勒天气雷达三维风场反演技术   总被引：27，自引：9，他引：27  

周海光  张沛源 《气象学报》2002,60(5):585-593

文中研究了笛卡尔坐标系下双多普勒天气雷达三维风场反演技术 ,提出了包括雷达原始资料的预处理 ,空间插值以及可靠性检验的新方法 ,提高了反演结果的可信度和精确度。使用模拟的双多普勒雷达体扫资料进行了反演试验 ,结果表明 :本文的方法能够比较真实地反映风场的三维结构 ,可以用于真实风场的反演。  相似文献   

Wind and Wave Data Analysis for the Aegean Sea - Preliminary Results     

Takvor H. Soukissian  Aristides M. Prospathopoulos  Chrysoula Diamanti 《Journal of Atmospheric & Ocean Science》2002,8(2):163-189

In this paper, a statistical analysis on wind and wave buoy measurements and wind and wave model forecasts obtained during a two-year period (1999-2001) is presented with reference to four characteristic near-shore sites of the Aegean Sea. The measurements are a main product of the "POSEIDON" system aiming at the monitoring and forecasting of the state of the Greek seas, operated by the National Centre for Marine Research (NCMR). Although the two-year period is rather short for a thorough analysis of the local wind and wave climate, yet the obtained results, presented herein for the first time, reveal some interesting features of the corresponding wave and wind characteristics. Comparisons between the measurements and the forecast results are also performed at the locations under consideration. It is found that (i) wind speeds obtained from the POSEIDON weather forecasting system are, in general, in agreement with the measurements, except for high wind speeds which are systematically underestimated, (ii) the WAM model can successfully follow the monthly and over year trend of the evolution of wind and wave characteristics, but face significant problems for efficient sea-state forecasting. Finally, the overall pattern of the wind/wave climate for the entire Aegean Sea as obtained from the models is presented by means of the spatial distribution of the mean annual wind and sea-state intensity.  相似文献   

Optimal design of passive energy dissipation systems based on H∞ and H2 performances     

J. N. Yang  S. Lin  J‐H. Kim  A. K. Agrawal 《地震工程与结构动力学》2002,31(4):921-936

Passive energy dissipation devices (EDDs), such as viscous dampers, viscoelastic dampers, etc., have been used to effectively reduce the dynamic response of civil infrastructures, such as buildings and bridges, subject to earthquakes and strong winds. The design of these passive energy dissipation devices (EDDs) involves the determination of the optimal locations and the corresponding capacities. In this paper, we present two optimal design methodologies for passive EDDs based on active control theories, including H_∞ and H₂ performances, respectively. The optimal design methodologies presented are capable of determining the optimal locations and the corresponding capacities of EDDs. Emphasis is placed on the application of linear matrix inequality (LMI) for the effective design of passive EDDs using the popular MATLAB toolboxes. One important advantage of the proposed approaches is that the computation of the structural response is not needed in the design process. The proposed optimal design methodologies have been applied to: (i) a 10‐storey building and a 24‐storey building both subject to earthquake excitations, and (ii) a 76‐storey wind‐excited benchmark building, to demonstrate the advantages of the proposed design methodologies over the conventional equal capacity design. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

河南省栾川县马圈一带银铅锌多金属找矿方向探讨     

宋要武 《华北地质》2002,(Z1)

马圈一带出露的主要地层为上元古界栾川群和中元古界官道口群 ,是Pb、Zn、Ag的主要含矿地层。燕山期花岗岩在空间上与矿化关系密切。矿体主要受北西向断裂控制 ,常分布在北西、北东向断裂构造交汇部位。根据地球化学特征、矿产分布规律和找矿标志 ,划分出百炉沟西凹—东凹—磨沟、百炉沟—黄花北沟—杨树凹等两个一级和银窝沟—大石渣沟—小石渣沟、板岔沟等两个二级找矿预测区。  相似文献   

井水位气压效率b值动态响应的断层-前兆场主应力组合模式          下载免费PDF全文

卜凡泉  杨燕 《地震工程学报》2002,24(4):356-360

统计鲁03，04井流水作业闰的气压效率b值发现，在华北及其周缘绝大多数地震前两井前兆异常形态各异，经分析井孔定位断层走向与地震前兆场主应力的组合模式不同是产生上述现象的根本原因。  相似文献   

南向行星际磁场事件与磁暴关系的研究   总被引：5，自引：5，他引：5       下载免费PDF全文

刘绍亮  李立文 《地球物理学报》2002,45(3):297-305

利用172-182年IMP-8飞船的太阳风观测资料和相应地磁活动性指数Dst和AE,研究了43个南向行星际磁场事件期间太阳风和磁层的耦合问题. 与这43个事件对应的地磁暴是中等的和强的磁暴(Dst＜-50nT). 结果表明:(1) 在43个事件中有11个(约占25.6髎)紧随激波之后,18个处于激波下游流场中(占42髎),其余14个(占33髎)和激波没有关连. 绝大多数事件都伴有太阳风动压和总磁场强度的增加;(2) 当行星际晨昏向电场强度EI＞-4mV/m时,只引起磁亚暴,对Dst指数没有明显影响. 仅当EI＜-5mV/m时,磁亚暴和磁暴才会同时出现;(3) 太阳风动压的增加会增强能量向环电流的输入,但不是密度和速度单独起作用,而是以PK=ρV2的组合形式影响能量的输入;(4) 虽然行星际磁场(IMF)南向分量BZ对太阳风和磁层的耦合起着关键作用,但IMF的BX和BY分量相对于BZ的大小对太阳风向磁层的能量传输也有一定影响. 当BX、BY相对BZ较大时能量耦合加强.  相似文献   

剥蚀及地幔作用下青藏高原隆升过程的数值模拟   总被引：7，自引：2，他引：7       下载免费PDF全文

李祖宁  傅容珊  黄建华 《地球物理学报》2002,45(4):516-524

修改了England和Mckenzie的黏性薄层流变模型中控制大陆形变的连续性方程,将剥蚀作用对高原隆升演化的影响直接引入该方程,并考虑下伏地幔小尺度对流对增厚岩石层的搬离作用对高原隆升演化后期的影响,用有限差分法直接模拟青藏高原隆升过程. 数值模拟结果所显示的高原隆升演化过程与实际观测资料吻合较好,揭示了高原隆升演化过程的非平稳和多阶段的特性;同时还表明上地幔小尺度对流对岩石层底部的搬离作用可能是最近8Ma以来高原快速隆升的主导机制.  相似文献