用地磁脉动日食效应探讨甚低纬Pc3-4地磁脉动源   总被引：1，自引：0，他引：1       下载免费PDF全文

王德驹  陈斯文  周国成 《地球物理学报》1999,42(4):460-464

在3次日食期间,利用甚低纬区和从低纬到甚低纬过渡区地面站进行的地磁脉动观测资料,分析了Pc3-4地磁脉动的南北分量（H）和东西分量（D）在H-D平面内矢端图主轴方向的变化．结果表明,当观测点纬度低于日全食带纬度时,H-D矢端图主轴有90°相移现象;当观测点纬度高于日全食带纬度时,则无这种现象．由此我们推测,甚低纬区和从低纬到甚低纬过渡区Pc3-4地磁脉动可能主要是过滤机制产生的．  相似文献   

Shaking Table Test Study on Dynamic Characteristics of Bridge Foundation Reinforcement on Slopes   总被引：3，自引：3，他引：0  

Lei D  Qi Zhihui  Jiang Guanlu  Wang Zhimeng  Li Anhong 《中国地震研究》2017,31(3):403-413

With the fast development of bridge construction in mountainous and seismic areas, it is necessary to conduct related research. Based on the design of a shaking table model test, here are the following test results:the filtering effect exists in soil and is affected by the dynamic constraint conditions, the amplitude is strengthened around the natural frequency and weakened in other frequency bands in the Fourier spectrum. Since the acceleration scaling effect occurred on a sloped surface, the acceleration response decreases from the outside to the inside in soil. The dynamic response is relatively strong near the slip surface in bedrock due to the reflection of seismic waves. The failure mode of landslide is decided by the slope angle and slipping mass distribution, and the test shows the front row stabilizing piles should keep a proper distance from bridge foundation so that seismic resistance can be guaranteed for the bridge foundation.  相似文献   

一种改进的线性预测滤波算法     

张靖  张晓君  江万寿  王建超  郭大海 《国土资源遥感》2011,22(1):52-56

对传统的线性预测算法进行改进,通过粗差剔除、初始点选取、特殊地形分析及光滑度检验等步骤提高了滤波精度.利用ISPRS发布的6组标准测试数据与原方法进行实验比较,结果证明,改进后的算法提高了滤波总精度以及地面点分类精度.  相似文献   

Effect of filtering on drift and anisotropy parameters determined by full correlation analysis     

H. Chandra 《Journal of Earth System Science》1989,98(4):327-338

The effect of low-pass filtering on the various drift and anisotropy parameters obtained by full correlation analysis of spaced receiver records is studied theoretically, assuming Gaussian correlation functions. A decrease in the characteristic velocityV _cis shown with increasing filtering, unlessV ≫ V _v, whenV _cincreases with filtering. The ratioV _c/V however shows an increase as the decrease in the true drift velocityV is steeper thanV _c. An increase in the size of the ground pattern with increasing filtering is also shown, while the axial ratio for anisotropic patterns shows a decrease. The results are verified with experimental data recorded earlier at Tiruchirapalli.  相似文献   

Smoothing and gap-filling of high resolution multi-spectral time series: Example of Landsat data     

《International Journal of Applied Earth Observation and Geoinformation》2017

This paper introduces a novel methodology for generating 15-day, smoothed and gap-filled time series of high spatial resolution data. The approach is based on templates from high quality observations to fill data gaps that are subsequently filtered. We tested our method for one large contiguous area (Bavaria, Germany) and for nine smaller test sites in different ecoregions of Europe using Landsat data. Overall, our results match the validation dataset to a high degree of accuracy with a mean absolute error (MAE) of 0.01 for visible bands, 0.03 for near-infrared and 0.02 for short-wave-infrared. Occasionally, the reconstructed time series are affected by artefacts due to undetected clouds. Less frequently, larger uncertainties occur as a result of extended periods of missing data. Reliable cloud masks are highly warranted for making full use of time series.  相似文献   

基于相干系数指导的自适应均值、中值滤波     

张鲜妮  王磊 《北京测绘》2013,(3):5-9

基于复数干涉质量与相干系数之间的关系,本文提出了一种基于相干系数指导的自适应滤波新方法。通过实验表明,相干系数指导的自适应滤波方法,在数据一致性、细节信息保持和边缘信息保持方面明显优于传统方法,相比之下去除噪声能力有所下降,残差点数目相对于固定窗口(大窗口)滤波较多,但是由于这种方法考虑了干涉噪声与相干系数之间的关系,所以滤波更符合实际,滤波综合性能较好。  相似文献   

Single-frequency precise point positioning with optimal filtering   总被引：7，自引：0，他引：7  

Anh Quan Le  Christian Tiberius 《GPS Solutions》2007,11(1):61-69

The accuracy of standalone GPS positioning improved significantly when Selective Availability was turned off in May 2000. With the availability of various public GPS related products including precise satellite orbits and clocks, and ionosphere maps, a single-frequency standalone user can experience even a further improvement of the position accuracy. Next, using carrier phase measurements becomes crucial to smoothen the pseudorange noise. In this contribution, the most critical sources of error in single-frequency standalone positioning will be reviewed and different approaches to mitigate the errors will be considered. An optimal filter (using also carrier phase measurements) will be deployed. The final approach will then be evaluated in a decently long static test with receivers located in different regions of the world. Kinematic experiments have also been performed in various scenarios including a highly dynamic flight trial. The accuracy, in general, can be confirmed at 0.5 m horizontal and 1 m vertical, with static tests. Ultimate results demonstrate an accuracy close to 2 dm (95%) for the horizontal position components and 5 dm (95%) for the vertical in the flight experiment.

Anh Quan LeEmail:

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智能优化方法与粒子滤波技术融合的分析与展望   总被引：1，自引：0，他引：1  

宫轶松  归庆明  孙付平  李保利 《海洋测绘》2009,29(2):74-77

智能优化算法通过模拟自然生态系统机制以解决复杂优化问题，粒子滤波成为解决非线性及非高斯动态系统最优估计问题的研究热点。若将多种优化算法结合使用，设计更好的滤波器参数寻优步骤，将会极大改善现有非线性滤波的估计性能。介绍了几种智能计算方法和粒子滤波方法，在此基础上，对智能优化方法与粒子滤波技术的融合进行了分析和讨论，并加以总结和展望。  相似文献   

一种船载海面通量观测的校正方法   总被引：2，自引：0，他引：2  

钱莉英  周乐义  周晓平 《海洋科学》1994,18(4):59-63

设计了一种用滤波法校正船载超声测风测量仪数据、计算海－气通量交换的方法。对１９８８，１９８９两年西太平洋海域考察期间超声测风测温仪的实测资料作了订正，订正了船体运动、特别是摇摆运动对风速的影响，用涡旋相关法计算了海面边界层的感热能量、动量通量、阻力系数和稳定度值。分析了海面上能量、阻力系数随大气状况的变化规律。计算结果表明，海面上的通量、阻力系数与水平风速和稳定度之间存在着合理的有规律的关系，证明  相似文献   

几个试验因子对细巧华哲水蚤清滤率和滤食率的影响   总被引：6，自引：0，他引：6  

陆开宏  吕耀平  林霞  郑祯  姚国琴 《海洋科学》2001,25(4):44-47

以象山港浮游桡足类优势种细巧华哲水蚤（Sinocalanus tenellus) 成体为试验动物投喂以大溪地等鞭金藻（Isochrysis galbona)，对其清滤率F（ml/个.h)和滤食率G（细胞／个.h)进行了实验测定，结果表明，温度，海水比重，食物浓度及试验动物密度的变化对细巧华哲水蚤清滤率和滤食率均有显著影响，水温15度，比重1．－1－，食物浓度150000个细胞／ml和试验动物密度．25个／ml的条件下，细巧华哲水蚤滤食率达到最大。  相似文献